String Obfuscator
Mask secrets and PII, or transform text with ROT13, leetspeak, and Unicode homoglyphs. Runs entirely in your browser — no server, no sign-up.
What this tool does
Mask or obfuscate a string right in your browser. Hide the middle of an API key, token, email, or any other sensitive value before a screenshot — or transform text with ROT13, leetspeak, or Unicode homoglyphs. Nothing is sent to a server: it runs locally, works offline, and needs no sign-up.
Modes
| Mode | What it does |
|---|---|
| mask (default) | Keeps the first N and last M characters visible and replaces the rest with a mask character. The classic way to redact a secret in a screenshot. |
| rot | Caesar / ROT-N rotation of the letters. The default shift is 13 (ROT13), which is its own inverse — apply it twice to get back the original. |
| leetspeak | Swaps letters for look-alike digits and symbols: a→4, e→3, i→1, o→0, s→5, t→7, b→8, g→9. |
| homoglyph | Swaps ASCII letters for identical-looking Unicode characters (mostly Cyrillic), so the text looks the same but is a different string. Useful for demoing homograph spoofing or defeating naive copy-paste. |
Masking options
- Mask character — the symbol used for the hidden part (default
*; try•or#). Only the first character you type is used. - Keep first N / Keep last N — how many characters to leave visible at each end. Whitespace stays visible too, so the masked shape still reads naturally. If the kept ends overlap, the whole string is shown unchanged.
Examples
| Input | Mode · Settings | Output |
|---|---|---|
sk-1234567890abcdef | mask · keep 5 / 4 | sk-12**********cdef |
password | mask · keep 1 / 1 · char • | p••••••d |
Hello, World! | rot · 13 | Uryyb, Jbeyq! |
elite hacker | leetspeak | 31173 h4ck3r |
paypal | homoglyph | looks like paypal, different bytes |
FAQ
Is it free and private?
Yes — your input never leaves your device, and it keeps working offline once the page has loaded.
Is masking reversible?
No. mask permanently removes the hidden characters,
which is exactly what you want for redaction. rot is reversible (ROT13 twice
returns the original); leetspeak and homoglyph are not cleanly reversible.
What is a homoglyph?
A character that looks identical to another but has a
different Unicode codepoint — e.g. the Latin a (U+0061) versus the Cyrillic
а (U+0430). They render the same but are different bytes.
Can I use ROT13 to secure data?
No — ROT13 is a toy cipher with no key. It hides text from a casual glance only; never use it for real secrets.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool string-obfuscator "sk-1234567890abcdef"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/string-obfuscator/?text=sk-1234567890abcdef&mode=mask&mask_char=%2A&keep_start=0&keep_end=0&rot_n=13Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.