Random String Generator - Create API, Token, UUID, Hex, PIN & Passwords
Generate random strings, passwords, API keys, tokens, PINs, hex codes, and UUIDs. Configurable length, character sets, and quantity. Cryptographically secure - powered by crypto.getRandomValues().
Generate Random String Online in 3 Steps
Configure your settings, click Generate, and copy the output - all in your browser with cryptographic security.
What is a Random String Generator?
A random string generator creates unpredictable combinations of characters used for passwords, tokens, IDs, and testing data. It helps generate secure and unique strings instantly.
Random String Generator - Free & Secure generate random string online
This random string generator creates cryptographically secure random strings using CSPRNG via the Web Crypto API. Unlike tools that rely on Math.random(), this generator uses crypto.getRandomValues() for true unpredictability - making the output suitable for passwords, API keys, authentication tokens, and security-critical applications.
Everything runs in your browser. No data is sent to any server. No account required. Configure your character sets, length, quantity, and toggle advanced options like ambiguous character exclusion and no-repeat constraints.
Key Features of this Random String Generator
This Random String Generator Tool vs. Other Random Token Generator
After creation, you can format generated strings to match naming conventions.
| Feature | Basic Generators | This Tool |
|---|---|---|
| Randomness source | Math.random() (predictable) | ✓ crypto.getRandomValues() (CSPRNG) |
| Strength meter | Rarely | ✓ Entropy bits + visual bar + combinations |
| Quick presets | Sometimes 1-2 | ✓ 6 presets including UUID v4 |
| Ambiguous exclusion | Sometimes | ✓ Toggle removes 0, O, o, l, I, 1 |
| No-repeat constraint | Rarely | ✓ Each character appears once max |
| Batch uniqueness | Rarely | ✓ Deduplication with max-attempts safety |
| Custom charset | Sometimes | ✓ Combinable with all presets |
| Privacy | Varies (server-side) | ✓ 100% browser-based, zero data sent |
Understanding Entropy & Security
Entropy measures how unpredictable a string is. It's calculated as log₂(charsetSize) × length in bits. A 16-character alphanumeric string (62 chars) has about 95 bits of entropy - far above the 80-bit minimum recommended for security-critical applications.
The strength meter uses five levels: Very Weak (below 28 bits), Weak (28-35), Fair (36-59), Strong (60-127), and Very Strong (128+ bits). For passwords, aim for at least 60 bits. For API keys and tokens, 128+ bits is ideal.
Developers often embed generated tokens in HTML during testing.
Common Use Cases of Secure Random token generator
You can generate unique usernames and then style them with fancy text.
Privacy & Security
This tool runs directly in your browser. Your text is never uploaded, stored, or sent to any server. Everything is processed locally on your device, keeping your data private.
FAQs – Random String Generator
Yes. The tool uses crypto.getRandomValues() - the Web Crypto API that browsers use for TLS encryption. This produces cryptographically secure pseudorandom numbers, unlike Math.random() which is predictable. A fallback to msCrypto is provided for older IE browsers, with Math.random() as a last resort only.
Five combinable sets: Uppercase (A-Z, 26 chars), Lowercase (a-z, 26 chars), Numbers (0-9, 10 chars), Symbols (!@#$%^&* and more, 30 chars), and Custom (any characters you enter). You can combine any or all of these together.
Password: 20 chars, all sets, excludes ambiguous. API Key: 32 chars, alphanumeric, excludes ambiguous. Token: 64 chars, lowercase + numbers. PIN: 6 digits only. Hex: 32 chars of 0-9a-f. UUID: generates a proper UUID v4 format string.
It removes characters that look similar in many fonts: 0 (zero) and O (oh), l (el) and 1 (one), and I (capital i). This makes strings easier to read, transcribe, and communicate verbally.
When enabled, each character in a single string can only appear once. If the requested length exceeds the charset size, the length is automatically capped with a warning. For example, numbers only (10 chars) can produce a maximum of 10 characters without repeats.
The strength meter calculates entropy in bits using log₂(charsetSize) × length. It shows five levels: Very Weak (below 28 bits), Weak (28-35), Fair (36-59), Strong (60-127), and Very Strong (128+). It also displays the total number of possible combinations.
Up to 100 strings in a single batch. You can enable "Each string must be unique" to ensure no duplicates. If the combination space is too small for the requested count, a warning explains how many unique strings could be generated.
No. All generation happens entirely in your browser using JavaScript. Nothing is stored, logged, or transmitted. The tool works offline once the page is loaded.
UUID v4 is a universally unique identifier format defined in RFC 4122. It has the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is a random hex digit and y is 8, 9, a, or b. Version 4 UUIDs are generated from random numbers and have approximately 5.32 × 10³⁶ possible values.
Yes. The layout is fully responsive - the configuration panel and output cards adapt to mobile screens. The slider, stepper, and all controls work on touch devices.
Start Generating Random Strings
Cryptographically secure. 6 presets. Batch generation. Entropy meter. Free, private, browser-based. Explore more tools in our Free Online Text Tools collection.
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