Gronsfeld cipher
ClientPolyalphabetic cipher with repeating decimal key.
Numeric-key Vigenère variant—digits 0–9 as shifts.
About Gronsfeld cipher
Numeric-key Vigenère variant—digits 0–9 as shifts. The interactive transform on this page runs in your browser tab—Toolcore does not need your paste for the core operation described above.
How to use this page
Paste or type in the main workspace, run the primary action from the toolbar, then copy or download the result. Use Load example when the page offers it, or URL prefill (?q= / ?qb=) so agents and tickets open the same input.
KFPMT
Common use cases
- Gronsfeld cipher for quick local checks without uploading data.
- Copy results into tickets, docs, or classroom notes.
Common mistakes to avoid
Unexpected input shape
See the intro and how-to notes for accepted formats.
FAQ
Is processing local?
Yes—this runs entirely in your browser.
Agent prefill?
Use q or qb for the main text field when supported.
More tools
Related utilities you can open in another tab—mostly client-side.
Porta cipher
ClientPorta self-reciprocal polyalphabetic cipher with keyword.
Vigenère cipher
ClientEncrypt or decrypt A–Z with a repeating keyword—classic polyalphabetic cipher locally.
ROT13 & Caesar cipher
ClientRotate Latin letters A–Z and a–z: ROT13 (self-inverse) or Caesar shift 0–25—other characters unchanged, local only.
Beaufort cipher
ClientBeaufort substitution cipher with repeating keyword.