Random String Generator
Generate random strings with customizable length and characters. Free, fast, and works entirely in your browser with no sign-up required.
Updated
Random String Generator
Generate cryptographically secure random strings, API keys, tokens, passwords and patterns with advanced customization.
Quick Presets
Generation Mode
Length
Character Sets
Active charset (62 chars)
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
Prefix & Suffix
Generation History (0)
Pattern Reference
X — uppercase letterx — lowercase letter0 — digitA — any from charseta — lowercase + digit-_. — literal characterExample: XXXX-0000-xxxx → KVTP-8341-mwqz
Privacy First
All strings are generated locally using your browser's crypto.getRandomValues(). No data is ever sent to a server.
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Frequently Asked Questions
Are random strings from this tool safe to use for API keys and passwords?
Yes. Every string is generated in your browser with crypto.getRandomValues(), the cryptographically secure random source the Web Crypto API exposes. That makes the output suitable for security-sensitive values like API keys, bearer tokens, and passwords. This matters because the common Math.random() is predictable and must never be used for secrets, even though many quick generators rely on it. Because generation happens locally, the keys are never uploaded or written to a server log, removing the risk of a credential being captured in transit. For real security, choose enough length and character types: a 16-character string mixing uppercase, lowercase, numbers, and symbols clears a high bar, while a short numeric PIN does not. Pick a preset like API Key or Bearer Token to start, then generate.
What is string entropy and how many bits do I need for a strong value?
Entropy measures how hard a string is to guess, expressed in bits. It is calculated as the string length multiplied by the base-2 logarithm of the character set size, so both longer strings and larger character sets raise it. The strength meter here uses that formula: it crosses into "Strong" around 100 bits and reaches "Very Strong" at 128 bits or more, with weaker scores below. As a practical target, 128 bits is the widely cited benchmark for secrets that should resist brute-force guessing. To hit it, add character types and increase length rather than relying on one alone. Remember the meter reflects the string in isolation, not how a specific system stores or rate-limits it. Generate a value and watch the meter to find a length that reaches your goal.
What is the difference between standard, pronounceable, and pattern generation?
The tool offers three modes for different needs. Standard draws each character at random from the sets you enable, giving maximum unpredictability for API keys, passwords, and tokens. Pronounceable alternates consonants and vowels to build memorable, easy-to-say strings like "nopaki" for codes a human has to read aloud or remember, at the cost of some randomness. Pattern builds output from a template so it follows a fixed shape: X becomes an uppercase letter, x a lowercase letter, 0 a digit, A any enabled character, a a lowercase letter or digit, and any other symbol such as a dash is kept as a literal separator. So "XXXX-0000" might yield "KVTP-8341". Choose Standard when guessability matters most, and Pattern when the value must match a required format. Select a mode and generate.
Why would I exclude ambiguous characters like 0, O, I, and l?
Certain characters look almost identical in many fonts: the digit 0 versus capital O versus lowercase o, and capital I versus lowercase l versus the digit 1. When a code is printed on a label, shown on screen, or read aloud, those look-alikes get misread and the value fails. The Exclude ambiguous option removes 0, O, o, I, l, and 1 from the pool so the strings you generate can be copied or typed by hand without confusion. It is ideal for coupon codes, license keys, voucher numbers, and anything a person handles directly. There is a small trade-off: a smaller character set slightly lowers entropy per character, which you can offset by adding a few more characters of length. Enable the option in settings before you generate codes meant for human use.
How do I generate many random strings at once and add a prefix like sk_live_?
Set the quantity field to produce up to 100 strings in a single batch, useful for seeding test fixtures, creating sample identifiers, or generating a list of unique codes. Each string can carry a prefix and a suffix that you define, so you can prepend something like sk_live_ to mimic the shape of a real secret key or append an environment tag. Length is adjustable up to 512 characters, either fixed or drawn randomly from a min and max range, and the No repeated characters option guarantees every character in a string is unique. When the batch is ready, copy a single string, copy them all together, or export the whole list as a TXT or CSV file. Enter your count, set any prefix or suffix, and generate the batch.
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About the Random String Generator
The Random String Generator creates unpredictable strings of any length and character mix, on demand. Whether you need a 32-character API key, a batch of test fixtures, a memorable passphrase, or an identifier that follows a fixed format like XXXX-0000, you set the rules and the tool produces strings that match. It is built for developers, QA engineers, and anyone who needs throwaway tokens, sample data, or hard-to-guess values without hand-typing them.
Every string is generated locally using your browser's crypto.getRandomValues(), the same cryptographically secure random source the Web Crypto API exposes. Nothing is uploaded, logged, or sent to a server, so the keys and tokens you create stay on your device. There is no sign-up and no installation.
Three ways to generate
The tool offers three generation modes, each suited to a different need:
- Standard — draws characters at random from the sets you enable. This is the right choice for API keys, passwords, and tokens where unpredictability matters most.
- Pronounceable — alternates consonants and vowels to produce memorable, easy-to-say strings (like
nopaki), useful for codes a human has to read aloud or remember. - Pattern — builds a string from a template so the output follows a fixed shape. In a pattern,
Xbecomes an uppercase letter,xa lowercase letter,0a digit,Aany enabled character,aa lowercase letter or digit, and any other character (such as-) is kept as a literal separator. For example,XXXX-0000-xxxxmight yieldKVTP-8341-mwqz.
Tuning the output
You control exactly which characters can appear. Toggle uppercase (A–Z), lowercase (a–z), numbers (0–9), and symbols independently, or paste your own custom charset to override them entirely. Two refinements help avoid common pitfalls:
- Exclude ambiguous characters removes the look-alikes
0,O,o,I,l, and1, so a code copied off a screen or printout is not misread. - No repeated characters guarantees each character in a string is unique, handy for short codes drawn from a limited alphabet.
Length is fully adjustable up to 512 characters, either as a fixed number or a random value within a min/max range. You can also generate up to 100 strings in a single batch and attach a prefix or suffix to each one — for instance, prefixing sk_live_ to mimic the shape of a real secret key. Built-in presets for API Key, Bearer Token, Password, PIN, Hex Color, and more configure all of these settings in one click.
Reading the strength meter
After you generate, a strength indicator estimates how hard the result would be to guess. It is based on entropy, calculated as the string length multiplied by the base-2 logarithm of the character set size — the standard measure of randomness expressed in bits. The meter scores from Very Weak to Very Strong, crossing into "Strong" around 100 bits and "Very Strong" at 128 bits or more. As a rule of thumb, more character types and greater length both raise entropy: a 16-character string using upper, lower, numbers, and symbols clears a high bar, while a short numeric PIN does not. The meter is a guide for choosing safer values, not a guarantee about any specific system.
Why client-side randomness matters
Generating secrets in the browser, rather than on a remote service, removes the risk that a credential is captured in transit or retained in server logs. Because crypto.getRandomValues() is a cryptographically secure pseudo-random number generator, its output is suitable for security-sensitive uses like tokens and passwords, unlike Math.random(), which is predictable and should never be used for secrets. When you are done, copy any single string, copy the whole batch, or export the results as a TXT or CSV file. A local generation history keeps your recent batches within reach during a session and is never persisted off your device.