Random String Generator
Generate batches of random strings with custom length, character groups or your own alphabet.
Results are provided as is, for general information. Check anything important before relying on it. See the Terms of Use.
About Random String Generator
Create batches of random text for test data, sample identifiers and other tasks that need configurable strings. Choose 1–100 strings, each 1–1024 characters long. Use uppercase letters, lowercase letters, numbers and symbols, or replace those groups with your own printable ASCII alphabet. The default is 10 strings of 16 letters or numbers. Each character is drawn independently from the effective alphabet; duplicates are allowed. Generate explicitly, then copy a single row or the whole batch. The tool runs on your device and does not save or upload generated text.
How Random String Generator works
Alphabet = distinct selected characters, minus optional look-alikes Each string = Length independent character draws Batch size = Quantity strings; duplicates are allowed
Each position uses the same effective alphabet. The sampler rejects an uneven tail of the random-number range before selecting a character, so alphabet positions have equal probability. Repeated characters in a custom alphabet do not add weight. With a single available character, every output is necessarily the same; random generation cannot create variation that the alphabet does not contain.
| Question | Working | Answer |
|---|---|---|
| Custom alphabet X, length 4, quantity 2 | Only X is available for each of the four positions in each string. | XXXX XXXX |
When to use Random String Generator
Random String Generator FAQ
How do I generate a random string?
Set Length and Quantity, select Character groups or Custom characters, then choose Generate strings. For example, a length of 16 and quantity of 10 creates ten rows, each containing sixteen characters. Changing a setting clears the previous batch so you do not copy results from older settings.
Can I use a custom alphabet?
Yes. Custom characters replaces the standard groups. It accepts printable ASCII letters, digits, punctuation and spaces. Repeated characters count once: aabc uses the same three-character alphabet as abc. Tabs, newlines and Unicode characters are rejected. Spaces count toward length and are preserved in displayed and copied results, including at the start or end.
Does selecting numbers guarantee a digit in every string?
No. Selecting a group makes its characters available. Every position is drawn independently from the combined alphabet, so a short string may not contain every selected group. Exclude look-alikes removes i, I, l, 1, O and 0 from either mode; you need at least one character left.
Are the strings unique?
No. Characters and entire strings may repeat. Small alphabets and short lengths make repeats more likely. Use the UUID Generator when you need UUID-formatted identifiers, and enforce uniqueness in your own system when duplicates cannot be accepted.
How are the random characters selected?
The browser supplies random values through crypto.getRandomValues. The shared sampler rejects values in an uneven remainder before selecting an alphabet position, avoiding modulo bias. If secure randomness is unavailable, generation fails with a message instead of switching to Math.random. This does not make a short or predictable alphabet a strong secret.
Does this evaluate password strength?
No. It focuses on batches, exact lengths and custom character alphabets. Use the Password Entropy Calculator to estimate strength. This tool does not implement token storage, expiry or access controls.
How do I copy a batch?
Copy all places one string per line on the clipboard, with no extra trailing newline. Each row also has its own Copy button. Duplicate rows and spaces are kept exactly. Generated strings stay only in page memory until you clear them, change settings or leave the page.