Random test string generator
Generate a random string of 1 to 4,096 characters from an alphabet you define, for test API keys, tokens or placeholder IDs.
- Runs in your browser
- No upload
- Result stays on your device
Privacy & limitsRuns in your browser. Nothing is uploaded.
Input content stays in this tab; Refentra does not upload or store it. Optional aggregate action counts are sent only with your usage consent. Clear the workspace when finished.
Supported profile: Web Crypto: 1–4,096 characters, alphabet 2–256 unique symbols; test string only.
Maximum text: 200,000 UTF-16 units; parser limits can be smaller. Worker time limit: 15 seconds (regex 1.5 seconds).
Check the input and the result
- Prepare and choose the operation
Set the length and the alphabet. Choose a URL-safe alphabet when the field you are filling in can't accept punctuation.
- Check a concrete example
Use this sample and compare the indicated result: length=8; alphabet=01 → /^[01]{8}$/
- Check the output before you reuse it
Check the permitted characters and the exact length before you use the value. Keep any secret out of shared URLs and screenshots.
Answers for this task
Is this an active API credential?
No. It only creates random text. An API provider has to register or issue credentials with permissions separately.
What should I check if the input fails?
Use a length of 1–4,096 and 2–256 distinct alphabet characters. Duplicate alphabet entries are merged, not weighted.
Where does this tool stop?
Entropy depends on the length and the size of the alphabet. A short binary string is not suitable as a high-value authentication secret.