Generate a Custom String
Build a random string from a chosen character set, with affixes. Runs entirely in your browser, so your data never leaves your device.
Output
The result appears here as you type.
How to use Generate a Custom String
- 1. Set the length. Type how many characters you want in the Length field. This is the only thing that decides how long the finished string will be, from a short code to a long token.
- 2. Choose a character set. Pick Letters and digits, Letters, Digits, Hexadecimal, Symbols, or Custom from the Characters select. Custom unlocks the Custom characters field so you can restrict output to an exact alphabet, like ACGT for a DNA-style string.
- 3. Add a prefix or suffix. Fill in Prefix or Suffix if the string needs to look like an existing ID format, such as a leading USR_ or a trailing -v1. Leave either blank to skip it.
- 4. Copy the generated string. Click generate and copy the result from the output pane. Regenerate as many times as you like; each run produces a fresh random string using the same settings.
When to use Generate a Custom String
Generate a Custom String is for building a random value from a precise character set rather than a generic default. Fixed prefixes and suffixes let the output match an existing naming scheme, and a custom alphabet lets you produce things a plain random generator cannot, like biological sequences or a restricted symbol set.
- Mocking DNA-like test data. A bioinformatics script expects sequences built only from A, C, G and T. Setting Custom characters to those four letters and a length of 12 produces a plausible-looking sequence for a fixture without touching real genomic data.
- Matching an internal ID format. Your ticketing system uses IDs like TASK-a8f3k2. Set the prefix to TASK-, pick Letters and digits, and set the length to six to produce values that slot straight into a seed script.
- Building placeholder API keys. A staging environment needs fake API keys with a recognizable prefix like sk_test_. Adding that as the Prefix and choosing Hexadecimal characters gives you a key-shaped string for a config file.
- Filling a spreadsheet column. You need 20 unique-looking codes for a demo spreadsheet, each wrapped the same way. Generate one, note the pattern, and repeat with the same length and character set for consistent-looking rows.
Examples
A DNA-like string
Input
Output
ACGTGGCATTAC
About the Generate a Custom String tool
Generate a Custom String runs as plain JavaScript in your browser tab, with no server behind it. Build a random string from a chosen character set, with affixes. Whatever you put in stays on your device from start to finish.
The tool is part of EditSafely's String Tools section, 159 single-purpose utilities built around the same idea: open the page, get the result, keep your data to yourself.
You can shape the output with 5 settings, including Length, Characters, Custom characters and Prefix, and the result refreshes the moment you change one. A worked example further down the page shows exactly what the tool produces for a real input.
That local-first design has practical benefits beyond privacy. The tool keeps working on a flaky connection once the page has loaded, results are instant because nothing round-trips to a server, and it is safe to use with confidential material.
Frequently asked questions
Does Generate a Custom String cost anything?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Does the generator send anything to a server?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
How do I get a different result?
Run the generator again. Each run is computed fresh on your device, and any options you change are applied to the next result immediately.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.