Convarso
    Free Online Tool

    Secure Random String Generator

    Generate cryptographically secure random strings locally — choose length, count, character sets, and one-click copy or download.

    WebCrypto powered
    100% local
    Custom charsets

    Preview

    Entropy: 95.3 bitsVery Strong

    Pool: 62 characters

    Generate Multiple

    Settings

    16

    Character Types

    Options

    What Is a Random String Generator?

    A random string generator creates sequences of characters with no predictable pattern. When powered by cryptographic randomness (as ours is), these strings are suitable for security-sensitive use cases like API keys, session tokens, passwords, and encryption keys.

    Unlike pseudo-random generators (Math.random), our tool uses the Web Crypto API which provides cryptographically secure random numbers. This means the output is unpredictable even to an attacker who knows the algorithm, making it safe for production security use.

    API keys, session tokens, test data, database seeds — developers need random strings constantly, and copy-pasting from /dev/urandom isn't exactly convenient. This generator creates strings of any length with configurable character sets (alphanumeric, hex, symbols, custom). It uses the Web Crypto API for proper randomness, and runs entirely in your browser.

    Key Features

    Cryptographically Secure

    Powered by the Web Crypto API (crypto.getRandomValues), every string is generated with true randomness — suitable for tokens, API keys, and security-sensitive applications.

    Fully Customizable

    Control length (4–128 chars), character types (lowercase, uppercase, numbers, symbols), custom character sets, prefix/suffix, and character exclusions. Build exactly the format you need.

    100% Client-Side

    All generation happens in your browser. No strings are sent to any server, logged, or stored. Your tokens and secrets stay completely private.

    Batch Generation

    Generate up to 100 strings at once. Copy all to clipboard, download as a text file, or separate with newlines, commas, or spaces for easy integration into scripts and databases.

    Entropy Analysis

    See real-time entropy (in bits) and a strength rating for every generated string. Verify that your tokens meet minimum security requirements before deployment.

    Smart Character Control

    Exclude visually similar characters (l, I, 1, O, 0) to avoid confusion in manual entry. Exclude ambiguous symbols. Require at least one character from each selected type.

    Who Is This Tool For?

    Developers

    Generate API keys, session tokens, CSRF tokens, database seeds, and test data. Custom character sets let you match any format specification (e.g., hex-only, base62, alphanumeric).

    DevOps & Sysadmins

    Create secure passwords for service accounts, encryption keys, configuration secrets, and environment variables. Batch-generate credentials for multiple environments.

    Product Managers

    Generate unique coupon codes, referral codes, or invite tokens. Use prefix/suffix options to add branding (e.g., "PROMO-XXXX-2025") while keeping the random portion secure.

    Security Engineers

    Verify entropy requirements, test input validation, and generate test vectors. The real-time entropy display confirms that generated strings meet your security policy.

    Entropy & Security Guide

    Entropy (bits)StrengthExample UseApprox. Length (a-zA-Z0-9)
    < 28WeakShort-lived test tokens~5 chars
    28–60FairCoupon codes, session IDs~10 chars
    60–80StrongAPI keys, access tokens~14 chars
    80+Very StrongEncryption keys, secrets~16+ chars

    Frequently Asked Questions

    4.8/ 5(127 ratings)

    Rated by real users — your feedback helps us improve