Security tools
ClientThis page is an index for deterministic security helpers: hashing, signing, token inspection, checksums, password and token generation, certificate inspection, compression, and identifier validation. Open a card for the dedicated route. Most tools stay client-side unless a tool page says otherwise.
If you are choosing between tokens, hashes, PEM blocks, checksums, and identifier checks, read Security checks before you share.
How this hub is organized
Each card opens a dedicated route—encryption and digests, JWT inspection, PKCE, TOTP, checksums, passwords, and validators. Check the execution badge on a card before you paste production secrets.
Browse security utilities
Cards follow the home catalog order for this category: start with crypto, JWT, PKCE, TOTP, SRI, bcrypt, file checksums, payment and bank number checks, PEM inspection, generators, compression, or validators.
Encrypt & decrypt
ClientEncrypt, decrypt, hash (AES, DES, RC4, Rabbit, TripleDES, MD5, SHA) and Base64—client-side.
HMAC (SHA-256 & more)
ClientHMAC-SHA-256/384/512/1 in the browser—hex or Base64 for webhooks, signing, and API docs.
File checksum & hash
ClientSHA-256, SHA-512, MD5, CRC-32, and more for a local file—verify downloads without uploading.
Hash identifier
ClientGuess digest type from hex length, Base64 shape, or bcrypt/Argon2 prefixes—heuristic, local only.
CRC-32 & CRC-32C
ClientIEEE CRC-32 and Castagnoli CRC32C on UTF-8 text or raw hex bytes—ZIP/PNG family vs iSCSI/protobuf; local only, complements file checksum for whole-file digests.
Adler-32 checksum
ClientRFC 1950 Adler-32 on UTF-8 text—decimal and hex output for zlib-style checksum checks in your browser.
Subresource Integrity (SRI)
ClientSHA-256/384/512 base64 integrity tokens for script and link tags—UTF-8 paste or local file; Web Crypto only.
CSP header builder
ClientBuild a Content-Security-Policy header from directive fields—copy for nginx, Express, or CDN configs locally.
Permissions-Policy builder
ClientBuild a Permissions-Policy header to allow or deny camera, geolocation, payment, and other browser features locally.
Referrer-Policy builder
ClientPick a Referrer-Policy value and copy the HTTP header—control referrer leakage locally.
Cross-origin policy headers
ClientBuild COOP, COEP, and CORP response headers for isolation and embed rules—in your browser.
HSTS header builder
ClientDraft Strict-Transport-Security with max-age, includeSubDomains, and optional preload—local only.
Compress & minify
ClientHTML, JS, CSS, XML, SQL, JSON minify; batch JPEG/WebP image compression.
JWT decode
ClientInspect JWT header and payload as JSON in browser; signature not verified.
JWT sign & verify
ClientSign HS256/384/512 JWTs or verify HMAC signatures in the browser—pair with JWT decode for claims.
JWT verify (RSA / ECDSA)
ClientVerify RS256/384/512 or ES256/384/512 JWTs with a PEM public key in the browser—Web Crypto only.
JWT sign (RSA / ECDSA)
ClientSign RS256/384/512 or ES256/384/512 JWTs with a PKCS#8 PEM private key in the browser—Web Crypto only.
JWT expiry check
ClientSee exp, nbf, and iat on a JWT vs your browser clock—expired or not-yet-valid hints; decode-only.
SSH key generator
ClientGenerate Ed25519 or RSA 2048 key pairs as PEM in the browser—optional OpenSSH public line for Ed25519.
OAuth PKCE generator
ClientRFC 7636 code_verifier plus S256 code_challenge (SHA-256, base64url)—Web Crypto in your tab, no upload.
TOTP / authenticator codes
ClientRFC 6238 time-based one-time passwords from a Base32 secret—HMAC-SHA1, otpauth URI and optional QR; local only.
Validate tools
ClientHub for format validators—Web3 Ethereum address (EIP-55) and hex private key checks; more routes over time.
Web3 address & key check
ClientValidate 0x address length and EIP-55 checksum; check 64-digit hex private key shape and secp256k1 range—browser-only.
Basic Auth header
ClientBuild Authorization Basic and curl -u from username and password—UTF-8 Base64 in your browser.
BIP39 mnemonic generator
ClientGenerate English BIP-39 recovery phrases (12–24 words) with browser CSPRNG—copy locally; not a wallet.
Password generator
ClientRandom passwords with length and character sets—generated in your browser.
PIN code generator
ClientGenerate 4–8 digit numeric PINs with crypto randomness in your browser—copy locally.
Password strength
ClientHeuristic password strength meter—length, charset mix, common weak-password warnings; local only.
Bcrypt hash & verify
Clientbcrypt password digests with adjustable cost (bcryptjs)—hash or verify $2a/$2b strings locally.
Random string generator
ClientRandom alphanumeric, hex, Base64 URL-safe, or custom tokens—entropy hint, local only.
Random integer generator
ClientUniform integers in a min–max range—optional unique draws, sort, Web Crypto; local only.
PEM / X.509 viewer
ClientDecode PEM certificates in the browser—subject, issuer, validity; paste only what you trust.
Password entropy (bits)
ClientEstimate entropy from charset pool size and length—education only.
Character pool size
ClientCount unique character classes in a password sample.
Playfair cipher
ClientClassic Playfair digraph cipher with a keyword—reversible substitution in your browser.
PEM block inspector
ClientList PEM certificate/key blocks and base64 size—browser-only, no upload.
PBKDF2 key derivation
ClientDerive keys with PBKDF2 (SHA-256/512) in the browser—hex and Base64 output for crypto workflows.
Shannon entropy
ClientBits of entropy per symbol for pasted text—password/passphrase analysis.
SSH public key fingerprint
ClientCompute SHA-256 OpenSSH-style fingerprint from a pasted public key line.
Random salt generator
ClientGenerate cryptographically random hex salt bytes for password hashing.
MD4 hash
ClientLegacy MD4 digest (hex) for interoperability checks—do not use for new security.
Constant-time string compare
ClientCompare two secrets in time independent of first mismatch position (educational).
otpauth:// URI parser
ClientParse TOTP/HOTP otpauth URIs into issuer, account, algorithm, and digits.
Base32 encode text
ClientEncode UTF-8 text to RFC 4648 Base32 (no padding) for secrets and TOTP seeds.
SHA3-256 hash
ClientSHA3-256 digest of UTF-8 text—local noble hash.
SHA3-512 hash
ClientSHA3-512 digest of UTF-8 text—local noble hash.
BLAKE2b hash
ClientBLAKE2b-512 digest of UTF-8 text—fast local hash.
BLAKE2s hash
ClientBLAKE2s-256 digest of UTF-8 text—local noble hash.
RIPEMD-160 hash
ClientRIPEMD-160 digest—legacy Bitcoin address era hash.
SHA-384 hash
ClientSHA-384 digest of UTF-8 text—local SHA-2 family hash.
SHA-224 hash
ClientSHA-224 digest of UTF-8 text—local SHA-2 family hash.
Keccak-256 hash
ClientKeccak-256 (Ethereum-style) digest—not SHA3 padding.
HKDF derive
ClientHKDF-SHA256 expand step—IKM and info as text fields.
scrypt parameter estimate
ClientEstimate scrypt memory and time from N, r, p—no hashing.
Argon2 parameter estimate
ClientEstimate Argon2 memory and iterations from m,t,p—no hashing.
PBKDF2 iteration estimate
ClientEstimate PBKDF2-HMAC-SHA256 time from iteration count—no derive.
bcrypt cost estimate
ClientEstimate bcrypt wall time from cost factor—no hashing.
Diceware passphrase
ClientGenerate random diceware-style words from inline wordlist.
JWK thumbprint
ClientRFC 7638 SHA-256 thumbprint of a JSON Web Key.
SHA-512 hash
ClientSHA-512 digest of UTF-8 text—local noble hash.
SHA-1 hash
ClientSHA-1 digest of UTF-8 text—legacy algorithm.
MD2 hash
ClientMD2 digest—historical checksum only.
FNV-1a 32-bit
ClientFowler–Noll–Vo 32-bit hash of UTF-8 bytes.
FNV-1a 64-bit
ClientFNV-1a 64-bit hash using BigInt arithmetic.
MurmurHash3 32-bit
ClientMurmurHash3 x86 32-bit—deterministic seed 0.
SipHash demo
ClientSipHash-2-4 style 64-bit MAC demo with fixed key.
CRC-16 Modbus
ClientModbus RTU CRC-16 over UTF-8 bytes.
CRC-16 XMODEM
ClientCRC-16/CCITT-FALSE (XMODEM) checksum.
Password entropy bits
ClientEstimate entropy from charset size and length.
bcrypt time estimate
ClientRough wall time from bcrypt cost factor.
HKDF expand info
ClientHKDF-SHA256 OKM with IKM and info labels.
Constant-time length check
ClientCompare two strings for equal UTF-8 byte length.
PEM Base64 normalize
ClientStrip PEM headers and re-wrap Base64 at 64 cols.
CSR PEM parse (basic)
ClientExtract subject CN from pasted CSR PEM if present.
MD5 hash
ClientMD5 digest of UTF-8 text—legacy checksum only.
Tiger128 hash
ClientTiger128 digest demo—educational non-crypto fingerprint.
Whirlpool512 hash
ClientWhirlpool512-style digest demo from SHA-512 truncation mix.
SHAKE128 hash
ClientSHAKE128 XOF digest—32-byte default output.
SHAKE256 hash
ClientSHAKE256 XOF digest—64-byte default output.
CRC-24
ClientCRC-24 checksum over UTF-8 bytes.
CRC-32 MPEG-2
ClientCRC-32/MPEG-2 checksum over UTF-8 bytes.
HMAC-MD5
ClientHMAC-MD5 MAC of message with UTF-8 key.
HMAC-SHA384
ClientHMAC-SHA384 MAC of message with UTF-8 key.
scrypt memory estimate
ClientEstimate scrypt RAM from N,r,p—no password hashing.
Argon2 memory estimate
ClientEstimate Argon2 memory KiB from m,t,p—no hashing.
Ed25519 public from seed (demo)
ClientDerive demo public key hex from 32-byte seed hex—educational.
X25519 shared secret (demo)
ClientDemo shared secret from two 32-byte hex private keys—educational XOR mix.
Passphrase strength
ClientScore passphrase length and charset diversity.
Password strength score
ClientNumeric 0–100 strength score from length and charset.
SHA3-224 digest
ClientSHA3-224 hash of UTF-8 text as lowercase hex.
SHA3-384 digest
ClientSHA3-384 hash of UTF-8 text as lowercase hex.
HMAC-SHA1
ClientHMAC-SHA1 of message with secret key.
HMAC-SHA512
ClientHMAC-SHA512 of message with secret key.
HMAC-SHA256
ClientHMAC-SHA256 of message with secret key.
Jenkins one-at-a-time hash
ClientBob Jenkins one-at-a-time 32-bit string hash.
MurmurHash3 128-bit demo
Client128-bit Murmur-style fingerprint demo from SHA-256 mix.
xxHash32 demo
Client32-bit xxHash-style digest demo for UTF-8 text.
Fletcher-32 checksum
ClientFletcher-32 checksum over UTF-8 bytes.
Fletcher-16 checksum
ClientFletcher-16 checksum over UTF-8 bytes.
CRC-64 ECMA-182
ClientCRC-64 with ECMA-182 polynomial over UTF-8.
CRC-32 BZIP2
ClientCRC-32/BZIP2 (PKZIP polynomial) checksum over UTF-8 text.
HAVAL-128 demo (3 pass)
ClientEducational 128-bit HAVAL-style fingerprint demo.
GOST R 34.11-2012 demo
Client256-bit GOST-style fingerprint demo from SHA-256 mix.
SM3 hash demo
ClientSM3-style 256-bit fingerprint demo for UTF-8 text.
JWT header decode
ClientDisplay JWT header JSON (display only—no verify).
JWT payload decode
ClientDisplay JWT payload JSON (display only).
Hamming weight (popcount)
ClientCount 1-bits in a non-negative integer.
Bit parity (even/odd)
ClientEven or odd parity of 1-bits in an integer.
XOR byte checksum
ClientXOR all UTF-8 bytes to one byte (hex).
CRC-16/CCITT-FALSE
ClientCRC-16/CCITT-FALSE over UTF-8 bytes.
CRC-16/Kermit
ClientCRC-16/Kermit checksum over UTF-8 text.
Adler-32 fold demo
ClientAdler-32 checksum over UTF-8 text.
HAS-160 demo digest
ClientEducational 160-bit HAS-160-style fingerprint demo.
Whirlpool-256 demo
Client256-bit Whirlpool-style demo digest.
Tiger-192 demo
Client192-bit Tiger-style demo digest.
RIPEMD-128 demo
Client128-bit RIPEMD-128-style demo digest.
SHA-0 demo digest
ClientEducational SHA-0-style 160-bit demo.
FNV-1a 128-bit demo
Client128-bit FNV-style fingerprint demo.
Entropy bits per character
ClientShannon entropy per char from pasted text.
HMAC-MD5 (demo)
ClientEducational HMAC-MD5 fingerprint demo (not for secrets).
HMAC-SHA384 (demo)
ClientHMAC-SHA384-style fingerprint demo from SHA-256 mix.
Bcrypt cost estimate
ClientEstimate bcrypt work factor timing table.
Scrypt params demo
ClientFingerprint from password + N,r,p demo params.
PBKDF2 iterations estimate
ClientRough time hint for iteration count.
Password entropy estimate
ClientEstimate bits from charset size and length.
Charset pool size
ClientCount alphabet size from selected character classes.
Seeded random hex
ClientDeterministic hex bytes from string seed.
CRC-32C (Castagnoli)
ClientCRC-32C checksum over UTF-8 text.
SUM8 checksum
Client8-bit additive checksum over UTF-8 bytes.
LRC checksum
ClientLongitudinal redundancy check (XOR of bytes).
Parity byte checksum
ClientEven parity bit packed into high bit of sum byte.
ROT5 (numbers)
ClientRotate decimal digits by 5 positions.
XOR with repeating key
ClientXOR UTF-8 bytes with repeating key; hex out.
Vigenère Kasiski (lite)
ClientFind repeated trigram spacing hints in ciphertext.
SRI hash generator
ClientBuild subresource integrity attribute demo.
PKCS#7 pad
ClientPad byte block to 16-byte boundary.
PKCS#7 unpad
ClientRemove PKCS#7 padding from hex bytes.
CRC-8 checksum
ClientCRC-8 with poly 0x07 on UTF-8 text.
CRC-24 checksum
ClientCRC-24 demo on UTF-8 input.
MD2 demo digest
ClientEducational MD2-style fingerprint demo.
MD4 demo digest
ClientEducational MD4-style fingerprint demo.
Timing-safe compare (demo)
ClientConstant-time string equality demo.
Constant-time XOR (demo)
ClientXOR two equal-length hex strings.
Bcrypt rounds table
ClientEstimated hash time by cost factor.
Password charset entropy
ClientEntropy bits from length and charset size.
Hash length identify
ClientGuess hash type from hex length.
HMAC-SHA512 (demo)
ClientHMAC-style SHA-512 fingerprint demo.
Scrypt work factor table
ClientEstimate scrypt N,r,p memory cost.
Argon2 params estimate
ClientEstimate Argon2 time/memory from params.
SHA-1 demo digest
ClientEducational SHA-1-style fingerprint demo.
Adler-32 demo checksum
ClientAdler-32 style checksum on UTF-8 text.
CRC-16-CCITT demo
ClientCRC-16 CCITT-FALSE on UTF-8 bytes.
CRC-16 Modbus demo
ClientModbus CRC-16 on UTF-8 input.
Password entropy estimate
ClientEntropy bits from length and charset.
Hash compare (hex)
ClientConstant-time-ish hex digest equality.
HMAC-SHA1 demo (lite)
ClientHMAC-style SHA-1 fingerprint demo.
MD5 demo fingerprint
ClientEducational MD5-style digest demo.
RIPEMD-160 demo (lite)
ClientEducational RIPEMD-160-style demo.
FNV-1a 64-bit demo
ClientFNV-1a 64-bit hash demo on text.
Jenkins hash demo
ClientBob Jenkins one-at-a-time hash demo.
MurmurHash3 demo (lite)
ClientSimplified MurmurHash3 32-bit demo.
PBKDF2 rounds estimate
ClientRough time vs iteration count.
Bcrypt cost estimate
ClientEstimated hash time by cost factor.
Scrypt params estimate
ClientEstimate scrypt N,r,p memory cost.
SHA-256 demo digest
ClientSHA-256 hash of UTF-8 text as lowercase hex.
SHA-384 demo digest
ClientSHA-384 hash of UTF-8 text as lowercase hex.
BLAKE2b demo (lite)
ClientBLAKE2b-512 hash of UTF-8 text as hex.
xxHash64 demo (lite)
Client64-bit xxHash-style digest demo for UTF-8 text.
PIN strength (lite)
ClientScore numeric PIN length and repetition.
Hex key length check
ClientValidate hex string byte length for AES keys.
XOR hex bytes (lite)
ClientXOR two equal-length hex strings.
SHA-512 demo digest
ClientSHA-512 hash of UTF-8 text as lowercase hex.
CityHash64 demo (lite)
Client64-bit CityHash-style fingerprint demo.
MurmurHash2 demo (lite)
Client32-bit Murmur2-style hash demo on UTF-8 text.
Password charset bits (lite)
ClientEntropy bits from length and charset size.
HMAC-SHA256 demo (lite)
ClientHMAC-SHA256 of message with secret key.
CRC-32C demo (lite)
ClientCastagnoli CRC-32C over UTF-8 bytes.
Fletcher-32 demo (lite)
ClientFletcher-32 checksum over UTF-8 bytes.
Scrypt memory estimate (lite)
ClientEstimate scrypt N,r,p memory cost.
SHA3-256 demo
ClientSHA3-256 hash of UTF-8 text as hex.
Keccak-256 demo
ClientKeccak-256 hash of UTF-8 text as hex.
RIPEMD-128 demo
ClientRIPEMD-128 style digest (first 16 bytes of RIPEMD-160).
Whirlpool demo
ClientWhirlpool-style 512-bit digest demo from UTF-8 text.
Bcrypt hash demo
ClientBcrypt hash of a password with cost 10.
JWT payload decode (lite)
ClientBase64url-decode JWT payload JSON only.
PEM format detect
ClientDetect PEM label and base64 payload length.
SHA-224 demo
ClientSHA-224 hash of UTF-8 text as hex.
Tiger hash demo
ClientTiger-style 192-bit digest demo.
Scrypt hash demo
ClientScrypt-style fingerprint demo (not full scrypt).
Poly1305 demo
ClientPoly1305-style MAC demo from message and key.
CRC-24 demo
Client24-bit CRC-style checksum demo.
GOST hash demo
ClientGOST-style 256-bit digest demo.
HAS-160 demo
ClientHAS-160 style 160-bit digest demo.
Password hash identify (lite)
ClientGuess hash type from prefix pattern.
MD4 hash demo
ClientMD4-style digest demo from UTF-8 text.
BLAKE2b hash demo
ClientBLAKE2b-256 digest of UTF-8 text.
Argon2 cost calculator
ClientEstimate Argon2 memory from m,cost params.
HMAC-SHA512 demo
ClientHMAC-SHA512 tag as hex from message and key.
MD5 demo digest
ClientMD5 hash of UTF-8 text as hex.
Adler-32 demo
ClientAdler-32 checksum demo for UTF-8 text.
SHAKE128 demo
ClientSHAKE128 XOF digest demo (32 bytes).
RIPEMD-256 demo
ClientRIPEMD-256 style digest demo.
MurmurHash3 demo
ClientMurmurHash3-style 32-bit fingerprint demo.
xxHash64 demo
ClientxxHash-style 64-bit fingerprint demo.
CityHash demo
ClientCityHash-style 64-bit fingerprint demo.
SHA-512 demo (lite)
ClientSHA-512 hash of UTF-8 text as hex.
SHA-256 demo (lite)
ClientSHA-256 hash of UTF-8 text as hex.
PBKDF2 params calculator
ClientEstimate PBKDF2 iterations from target ms.
Scrypt params calculator
ClientEstimate scrypt memory from N,r,p.
SHA-1 demo digest (lite)
ClientSHA-1 hash of UTF-8 text as hex.
SHA-384 demo hash (lite)
ClientSHA-384 hash of UTF-8 text as hex.
RIPEMD-320 hash demo
ClientRIPEMD-320 style digest demo for text.
SipHash64 demo (lite)
ClientSipHash-style 64-bit fingerprint demo.
FNV-1a 64 demo
ClientFNV-1a 64-bit hash demo for UTF-8 text.
CRC-8 checksum demo
ClientCRC-8 demo checksum for UTF-8 bytes.
CRC-16 demo (lite)
ClientCRC-16-CCITT demo for UTF-8 text.
DJB2 hash demo (lite)
ClientDJB2 string hash demo.
Jenkins one-at-a-time demo
ClientJenkins OAAT hash demo for text.
CRC32C checksum demo
ClientCastagnoli CRC32C demo for UTF-8 text.
HMAC-SHA1 tag demo
ClientHMAC-SHA1 tag as hex from message and key.
HMAC-MD5 tag demo
ClientHMAC-MD5 tag as hex from message and key.
Entropy bits estimate
ClientShannon entropy bits per character.
Password bits estimate (lite)
ClientEntropy bits from length and charset size.
PBKDF2 iter estimate (lite)
ClientSuggest iterations from target milliseconds.
MD2 demo (lite)
ClientLegacy MD2 digest demo—educational only.
Adler-32 checksum (DP)
ClientAdler-32 over UTF-8 text.
Fletcher-16 checksum (DP)
Client16-bit Fletcher checksum demo.
Jenkins one-at-a-time demo
ClientOne-at-a-time hash demo for strings.
MurmurHash demo
ClientSimplified Murmur-style 32-bit hash.
xxHash demo (lite)
ClientSimplified xxHash-style 32-bit output.
CityHash demo (lite)
ClientCityHash-inspired 64-bit-ish demo.
SHA-512 demo (lite)
ClientEducational 512-bit-style digest demo.
CRC-16 checksum (DQ)
ClientCRC-16-CCITT over UTF-8 text.
CRC-8 checksum (DQ)
ClientSimple CRC-8 over byte values.
FNV-1a hash (DQ)
Client32-bit FNV-1a hash demo.
DJB2 hash (DQ)
ClientClassic djb2 string hash demo.
SDBM hash (DQ)
ClientSDBM string hash demo.
XOR checksum (DQ)
ClientXOR of all byte values.
Parity check (DQ)
ClientEven parity bit for ASCII text.
Luhn check digit (DQ)
ClientCompute Luhn check digit for body.
Sum bytes (DQ)
ClientSum of UTF-8 byte values mod 256.
Rotating hash (DQ)
ClientRotate-xor hash demo for strings.
Adler-32 checksum
ClientCompute Adler-32 checksum demo.
MD5 demo hash
ClientMD5 digest demo (not for security).
SHA-1 demo hash
ClientSHA-1 digest demo (legacy).
CRC32C demo
ClientCastagnoli CRC32C checksum demo.
HMAC-SHA256 demo
ClientHMAC-SHA256 demo with key (educational).
Password entropy estimate
ClientEstimate bits of entropy from charset size.
Bcrypt rounds hint
ClientEstimate bcrypt work factor timing hint.
JWT payload decode
ClientBase64url-decode JWT payload (no verify).
PEM header parse
ClientIdentify PEM block type from header.
Salt length recommend
ClientRecommend salt bytes for hash algorithms.
FNV-1a hash
ClientCompute 32-bit FNV-1a hash demo.
CRC-16 hash
ClientCRC-16-CCITT checksum demo.
CRC-24 hash
ClientCRC-24 checksum demo (OpenPGP poly).
SHA-384 demo
ClientSHA-384 digest via Web Crypto demo.
SHA-512 demo
ClientSHA-512-style digest demo (educational).
Luhn check digit
ClientCompute Luhn check digit for a number.
Mod 11 check digit
ClientCompute mod 11 check digit (ISBN-10 style).
Sum8 checksum
Client8-bit additive checksum of UTF-8 bytes.
Hash length hint
ClientGuess algorithm from hex digest length.
XOR checksum
ClientXOR of all UTF-8 bytes.
CRC-8 checksum
ClientCRC-8 Dallas/Maxim style demo checksum.
CRC32C demo
ClientCastagnoli CRC32C demo checksum.
Adler-32 checksum
ClientAdler-32 checksum demo.
DJB2 hash
ClientDJB2 string hash demo.
SDBM hash
ClientSDBM string hash demo.
Parity check
ClientEven/odd parity bit for byte string.
Bcrypt rounds hint
ClientEstimate bcrypt work factor from hash prefix.
Salt length hint
ClientRecommend salt byte length for hashing.
Password entropy estimate
ClientEntropy bits from charset size and length.
HMAC-SHA256 demo
ClientEducational HMAC-style fingerprint demo.
FNV-1a hash
Client32-bit FNV-1a string hash demo.
SDBM hash
ClientSDBM string hash demo.
CRC-16 CCITT
ClientCRC-16-CCITT (0xFFFF init) demo.
CRC-16 Modbus
ClientCRC-16 Modbus (0xFFFF init, reflected).
MD5 demo fingerprint
ClientEducational MD5-style fingerprint demo.
SHA-1 demo fingerprint
ClientEducational SHA-1-style fingerprint demo.
SHA-256 short demo
ClientFirst 16 hex chars of SHA-256-style demo.
XOR checksum
ClientXOR byte checksum of UTF-8 text.
Entropy estimate
ClientShannon entropy bits per character.
Luhn check digit
ClientCompute Luhn check digit for digit string.
DJB2 hash
ClientDJB2 string hash demo.
CRC-32 demo
ClientCRC-32 IEEE-style demo checksum.
Adler-32 demo
ClientAdler-32 checksum demo.
HMAC demo fingerprint
ClientEducational HMAC-style fingerprint demo.
Bcrypt cost estimate
ClientEstimated bcrypt iterations from cost factor.
Password entropy bits
ClientEstimate entropy from charset size and length.
Base64 decode
ClientDecode standard Base64 to UTF-8.
Base64 encode
ClientEncode UTF-8 to standard Base64.
Sum8 checksum
Client8-bit additive checksum of UTF-8 bytes.
CRC-8 demo
ClientCRC-8 demo with poly 0x07.
FNV-1a hash demo
ClientFNV-1a 32-bit hash demo (not a password hash).
SDBM hash demo
ClientSDBM string hash demo.
CRC-16 CCITT demo
ClientCRC-16-CCITT demo with polynomial 0x1021.
XOR checksum demo
ClientXOR of UTF-8 bytes as an 8-bit demo checksum.
Hash length hint
ClientGuess MD5/SHA-1/SHA-256 from hex digest length.
Luhn check digit
ClientCompute the Luhn check digit for a digit body.
Shannon entropy demo
ClientShannon entropy in bits per character.
Fletcher-16 demo
ClientFletcher-16 checksum demo.
CRC-32C demo
ClientCastagnoli CRC-32C demo (poly 0x82f63b78).
HMAC fingerprint demo
ClientEducational keyed fingerprint—not HMAC-SHA256.
MurmurHash3 demo
ClientSimple Murmur-like 32-bit hash demo (not cryptographic).
Jenkins one-at-a-time hash
ClientJenkins one-at-a-time string hash demo.
CRC-24 demo
ClientCRC-24 demo with polynomial 0x864CFB.
16-bit sum checksum
Client16-bit one's complement sum demo.
Hash prefix detect
ClientDetect $2a$ bcrypt, sha256$, etc. from prefix.
Luhn validate
ClientFull Luhn validation on digit strings.
Character entropy bits
ClientShannon entropy in bits per character.
Fletcher-32 demo
ClientFletcher-32 checksum demo.
CRC-64 demo
ClientSimplified CRC-64 demo (educational).
Keyed hash demo
ClientEducational keyed fingerprint—not HMAC-SHA256.
SDBM hash demo
ClientSDBM string hash demo (non-cryptographic).
DJB2 hash demo
ClientDJB2 string hash demo (non-cryptographic).
FNV-1a demo
ClientFNV-1a 32-bit hash demo.
CRC-16 demo
ClientCRC-16-CCITT demo (poly 0x1021).
Adler-32 demo
ClientAdler-32 checksum demo.
MD5 length hint
ClientShow MD5 hex length and charset (no hash computed).
SHA-1 length hint
ClientShow SHA-1 hex length and charset (no hash computed).
XOR byte checksum
ClientXOR of all UTF-8 bytes demo.
Even parity bit
ClientEven parity bit for UTF-8 byte count.
Password length check
ClientCharacter and byte length of a password string.
Jenkins hash demo
ClientJenkins one-at-a-time hash demo (non-cryptographic).
Bernstein hash demo
ClientBernstein times-33 hash demo (non-cryptographic).
FNV-1 demo
ClientFNV-1 32-bit hash demo.
CRC-8 demo
ClientCRC-8 demo (poly 0x07).
16-bit sum checksum
ClientSimple 16-bit additive checksum demo.
SHA-256 length hint
ClientShow SHA-256 hex length and charset (no hash computed).
SHA-512 length hint
ClientShow SHA-512 hex length and charset (no hash computed).
8-bit add checksum
Client8-bit additive checksum with carry fold demo.
Luhn validate demo
ClientValidate a digit string with the Luhn mod 10 algorithm.
Password entropy hint
ClientRough Shannon entropy estimate for a password string.
SDBM hash demo
ClientSDBM hash demo (non-cryptographic).
DJB2 hash demo
ClientDJB2 hash demo (non-cryptographic).
FNV-1a demo
ClientFNV-1a 32-bit hash demo.
CRC-16 demo
ClientCRC-16-CCITT demo (poly 0x1021).
MurmurHash3 demo
ClientMurmurHash3 32-bit demo (simplified).
MD5 length hint
ClientShow MD5 hex length and charset (no hash computed).
XOR checksum
Client8-bit XOR checksum demo.
Luhn check digit
ClientCompute Luhn check digit for a digit string.
Password length check
ClientCharacter and byte length of a password string.
Fletcher-32 demo
ClientFletcher-32 checksum demo.
Jenkins hash demo
ClientJenkins one-at-a-time hash demo (non-cryptographic).
FNV-1 demo
ClientFNV-1 32-bit hash demo.
CRC-8 demo
ClientCRC-8 demo (poly 0x07).
CRC-32C demo
ClientCRC-32C (Castagnoli) demo.
Adler-32 demo
ClientAdler-32 checksum demo.
SHA-256 length hint
ClientShow SHA-256 hex length and charset (no hash computed).
8-bit add checksum
ClientSum bytes mod 256 demo.
Luhn validate demo
ClientPass/fail Luhn check on a digit string.
Password entropy hint
ClientRough entropy estimate from charset size and length.
16-bit sum checksum
ClientSum bytes into 16-bit word demo.
Jenkins hash demo
ClientJenkins one-at-a-time hash demo (non-cryptographic).
FNV-1 demo
ClientFNV-1 32-bit hash demo.
CRC-8 demo
ClientCRC-8 demo (poly 0x07).
CRC-32C demo
ClientCRC-32C (Castagnoli) demo.
Adler-32 demo
ClientAdler-32 checksum demo.
SHA-256 length hint
ClientShow SHA-256 hex length and charset (no hash computed).
8-bit add checksum
ClientSum bytes mod 256 demo.
Luhn validate demo
ClientPass/fail Luhn check on a digit string.
Password entropy hint
ClientRough entropy estimate from charset size and length.
16-bit sum checksum
ClientSum bytes into 16-bit word demo.
SDBM hash demo
ClientSDBM hash demo (non-cryptographic).
FNV-1a demo
ClientFNV-1a 32-bit hash demo.
CRC-16 demo
ClientCRC-16 demo (poly 0x8005).
DJB2 hash demo
ClientDJB2 string hash demo.
MurmurHash demo
ClientSimplified MurmurHash3 32-bit demo.
Fletcher-32 demo
ClientFletcher-32 checksum demo.
MD5 length hint
ClientShow MD5 hex length and charset (no hash computed).
XOR checksum
ClientXOR all bytes demo checksum.
Luhn check digit
ClientCompute the Luhn check digit for a digit string.
Password length check
ClientPass/fail common minimum password lengths.
Jenkins hash demo
ClientJenkins one-at-a-time hash demo (non-cryptographic).
FNV-1 demo
ClientFNV-1 32-bit hash demo (not FNV-1a).
CRC-8 demo
ClientCRC-8 demo (poly 0x07).
Adler-32 demo
ClientAdler-32 checksum demo.
Pearson hash demo
ClientPearson hash demo with 256-byte table.
BKDR hash demo
ClientBKDR string hash demo.
RS hash demo
ClientRobert Sedgwick string hash demo.
Additive checksum
ClientSum all bytes modulo 256 demo checksum.
Mod 10 check digit
ClientCompute GS1 mod 10 check digit for digits.
SHA-1 length hint
ClientShow SHA-1 hex length and charset (no hash computed).
AP hash demo
ClientArash Partow hash demo (non-cryptographic).
DJB2a hash demo
ClientDJB2 variant with xor-first (non-cryptographic).
CRC-24 demo
ClientCRC-24 demo (poly 0x864CFB).
CRC-32 demo
ClientCRC-32 IEEE demo (poly 0xEDB88320).
FNV-1a 64 hint
ClientShow FNV-1a 64-bit hex length hint (no hash computed).
Parity byte
ClientXOR parity byte over UTF-8 bytes demo.
Mod 11 check digit
ClientCompute mod 11 check digit (ISBN-style weights).
SHA-384 length hint
ClientShow SHA-384 hex length hint (no hash computed).
SHA-512 length hint
ClientShow SHA-512 hex length hint (no hash computed).
Hsieh hash demo
ClientPaul Hsieh SuperFastHash demo (non-cryptographic).
SDBM hash demo
ClientSDBM string hash demo (non-cryptographic).
Jenkins hash demo
ClientBob Jenkins one-at-a-time hash demo (non-cryptographic).
CRC-16 demo
ClientCRC-16 CCITT demo (poly 0x1021).
CRC-8 demo
ClientCRC-8 demo (poly 0x07).
XOR checksum
ClientXOR all UTF-8 bytes demo checksum.
Adler-32 demo
ClientAdler-32 checksum demo (non-cryptographic).
Luhn check digit
ClientAppend Luhn mod 10 check digit to digits.
SHA-1 length hint
ClientShow SHA-1 hex length hint (no hash computed).
MD5 length hint
ClientShow MD5 hex length hint (no hash computed).
Pearson hash demo
ClientPearson-style byte hash demo (non-cryptographic).
FNV-1a hash demo
ClientFNV-1a 32-bit string hash demo (non-cryptographic).
DJB2 hash demo
ClientDJB2 string hash demo (non-cryptographic).
CRC-32 demo
ClientCRC-32 IEEE demo (poly 0xEDB88320).
MurmurHash3 demo
ClientMurmurHash3-style 32-bit demo (non-cryptographic).
Sum bytes checksum
ClientSum all UTF-8 bytes modulo 256 demo.
Even parity bit
ClientEven parity bit for UTF-8 byte stream demo.
Mod 10 check
ClientValidate GS1 mod 10 check digit on digits.
SHA-256 length hint
ClientShow SHA-256 hex length hint (no hash computed).
SHA-512 length hint
ClientShow SHA-512 hex length hint (no hash computed).
Rolling hash demo
ClientSimple rolling hash over character codes demo.
FNV-1 hash demo
ClientFNV-1 32-bit string hash demo (non-cryptographic).
SDBM hash demo
ClientSDBM string hash demo (non-cryptographic).
CRC-16 demo
ClientCRC-16 CCITT demo (poly 0x1021).
Jenkins hash demo
ClientBob Jenkins one-at-a-time 32-bit hash demo.
XOR checksum
ClientXOR all UTF-8 bytes demo.
Adler-32 demo
ClientAdler-32 checksum demo (non-cryptographic).
Luhn check digit
ClientAppend GS1 mod 10 check digit to digits.
MD5 length hint
ClientShow MD5 hex length hint (no hash computed).
SHA-1 length hint
ClientShow SHA-1 hex length hint (no hash computed).
Polynomial hash demo
ClientBase-31 polynomial string hash demo.
FNV-1a hash demo
ClientFNV-1a 32-bit string hash demo (non-cryptographic).
DJB2 hash demo
ClientDJB2 string hash demo (non-cryptographic).
CRC-32 demo
ClientCRC-32 IEEE demo (poly 0xEDB88320).
Pearson hash demo
ClientPearson 8-bit string hash demo.
Sum bytes checksum
ClientSum all UTF-8 bytes modulo 256 demo.
Mod 10 check
ClientValidate GS1 mod 10 check digit on digits.
SHA-256 length hint
ClientShow SHA-256 hex length hint (no hash computed).
SHA-512 length hint
ClientShow SHA-512 hex length hint (no hash computed).
Rolling hash demo
ClientBase-256 rolling hash over string demo.
AP hash demo
ClientAP (Arash Partow) string hash demo.
FNV-1 hash demo
ClientFNV-1 32-bit string hash demo (non-cryptographic).
SDBM hash demo
ClientSDBM string hash demo (non-cryptographic).
Jenkins hash demo
ClientBob Jenkins one-at-a-time hash demo.
CRC-16 demo
ClientCRC-16 CCITT demo (poly 0x1021).
CRC-8 demo
ClientCRC-8 demo (poly 0x07).
Adler-32 demo
ClientAdler-32 checksum demo (non-cryptographic).
Fletcher-16 demo
ClientFletcher-16 checksum demo.
Luhn check digit generate
ClientAppend GS1 mod 10 check digit to digits.
MD5 length hint
ClientShow MD5 hex length hint (no hash computed).
XOR checksum
ClientXOR all UTF-8 bytes demo checksum.
FNV-1a hash demo
ClientFNV-1a 32-bit string hash demo (non-cryptographic).
DJB2 hash demo
ClientDJB2 string hash demo (non-cryptographic).
MurmurHash demo
ClientMurmurHash3-style 32-bit demo (non-cryptographic).
CRC-32 demo
ClientCRC-32 IEEE demo (poly 0xEDB88320).
CRC-32C demo
ClientCRC-32C Castagnoli demo.
Pearson hash demo
ClientPearson 8-bit hash demo (non-cryptographic).
Sum bytes checksum
ClientSum all UTF-8 bytes demo checksum.
Mod 10 check digit generate
ClientAppend GS1 mod 10 check digit to digits.
SHA-256 length hint
ClientShow SHA-256 hex length hint (no hash computed).
Parity bit
ClientEven parity bit for UTF-8 bytes demo.
Nearby workflows on Toolcore
- Encrypt & decrypt — for AES, hashes, and Base64 experiments on pasted text.
- JWT decode — to read claims without verifying signatures here.
- Password generator — before you hash throwaway samples on the bcrypt page.
- Validators hub — for Web3 and other format checks beside crypto tabs.
Common use cases
- Open JWT decode when you need header and payload JSON from a signed token—remember verification is not performed here.
- Use HMAC or crypto when reproducing webhook signatures or comparing hash outputs from docs.
- Use file checksum when verifying a download against a published SHA-256 or MD5 without uploading the file.
- Use CRC-32 when you need IEEE or Castagnoli CRC32C on pasted UTF-8 or hex bytes—distinct from cryptographic hashes and from whole-file checksum in the file tool.
- Use IBAN validate when you need MOD-97-10 and length checks locally—no bank directory lookup.
- Use ABA routing checker when you need the MICR checksum on a nine-digit Fed routing number—still verify institution-specific routines with your bank.
- Use payment card checker when you need mod 10 plus a Visa/Mastercard/Amex/Discover-style prefix hint from public BIN ranges—still only digits-in-browser.
- Use ISBN validate when you need ISBN-10 / ISBN-13 checksums or 978↔ISBN-10 conversion without a publisher API—identifiers only.
- Use OAuth PKCE when you need a fresh code_verifier and S256 code_challenge pair for a public client flow.
- Use TOTP when you need RFC 6238 codes from a Base32 secret—compare against your IdP or build otpauth URIs without uploading secrets.
- Use SRI when you need sha256/sha384/sha512 integrity tokens for script or link tags from the exact bytes you will serve.
- Use bcrypt when you need slow password digests or to verify a candidate password against an existing $2a/$2b hash locally.
- Jump to Validate tools for Web3 address checks and similar format guards, then return here for other security utilities.
Common mistakes to avoid
Pasting live secrets into shared machines
Processing is local on Toolcore, but screen visibility and clipboard history still matter—prefer redacted samples.
Assuming JWT decode implies trust
Decoding only shows claims; signature and audience checks belong in your application code.
FAQ
Where are format validators?
The validators hub is at /tools/validate (Web3 and more). It is listed below with the other security tools.
Is data sent to a server?
These tools run in your browser unless a specific page documents otherwise.