Bearer Token Generator
Generate secure random bearer tokens for OAuth 2.0, API authentication, and access control with multiple encoding formats
Our bearer token generator creates secure random bearer tokens for OAuth 2.0 authentication, API access control, and session management. Generate bearer tokens in multiple formats (Base64URL, Base64, Hex, Alphanumeric) with configurable byte lengths (16-128 bytes) using cryptographically secure random number generation (CSPRNG). Perfect for OAuth 2.0 implementations, REST API authentication, access token generation, and API security testing. Bearer tokens are used in HTTP Authorization headers (Authorization: Bearer
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What is a Bearer Token Generator?
A bearer token generator creates secure random tokens used for OAuth 2.0 authentication and API access control. Bearer tokens are the most common type of access token in OAuth 2.0, transmitted in HTTP Authorization headers as "Bearer
Our generator supports multiple encoding formats: Base64URL (RFC 4648, URL-safe, no padding) is the OAuth 2.0 standard, Base64 (traditional with + and /), Hex (lowercase hexadecimal), and Alphanumeric (0-9, a-z, A-Z only). Token byte length is configurable from 16 bytes (128 bits) to 128 bytes (1024 bits), with 32 bytes (256 bits) recommended for most applications balancing security and performance. Use bearer token generation for OAuth 2.0 server development, API authentication testing, access token generation, session management, microservices authorization, and security testing. All tokens include entropy calculations and strength assessments to ensure adequate security.
Bearer Token Generator Configuration
Count (1-50 Tokens)
Byte Length (16-128 bytes)
Encoding Format
How to Generate Bearer Tokens
[STEP 1] Configure Token Parameters
Choose count (1-50 tokens) and byte length (16-128 bytes). For OAuth 2.0 access tokens, use 32 bytes with Base64URL encoding. For high-security applications requiring strong entropy, use 64 bytes. For simple API authentication, 16-32 bytes is sufficient. Consider your security requirements and HTTP header size constraints.
[STEP 1] Select Encoding Format
Choose Base64URL for OAuth 2.0 compliance and URL safety (recommended). Use Base64 for compatibility with legacy systems. Select Hex for hexadecimal representation (common in debugging). Choose Alphanumeric for human-readable tokens without special characters. Base64URL provides the best balance of compactness and compatibility.
[STEP 1] Generate & Copy Tokens
Click EXECUTE GENERATION to create bearer tokens with CSPRNG security. Each token displays with a Copy button for easy clipboard access. Tokens show their byte length, entropy bits, and strength assessment (weak/fair/good/strong/very_strong). All tokens use PHP's random_bytes for cryptographic randomness.
[STEP 1] Use in API Authentication
Copy tokens for API testing with "Authorization: Bearer
Bearer Token Best Practices
- _ HTTPS Only - Always transmit bearer tokens over HTTPS/TLS. Tokens sent over unencrypted HTTP can be intercepted via man-in-the-middle attacks. Never embed tokens in URLs (visible in browser history, server logs, and referrer headers). Use Authorization headers exclusively.
- _ Sufficient Entropy - Use minimum 128 bits (16 bytes) of entropy for bearer tokens. OAuth 2.0 recommends 256 bits (32 bytes). Higher entropy makes tokens resistant to brute-force guessing. Our generator uses CSPRNG (random_bytes) ensuring unpredictability and cryptographic security.
- _ Short Token Lifetimes - Set expiration times for bearer tokens (1 hour typical for access tokens). Implement refresh tokens for longer sessions. Store expiration timestamps server-side and validate on each request. Expired tokens should be rejected immediately. Short lifetimes limit exposure if tokens are compromised.
- _ Secure Storage - Store bearer tokens securely server-side (database with encryption at rest). Never store tokens in client-side JavaScript localStorage (vulnerable to XSS). Use httpOnly cookies for web applications. Associate tokens with user IDs, permissions, and expiration times. Hash tokens before storage for additional security.
- _ Token Revocation - Implement token revocation mechanisms. Maintain a database of active tokens that can be invalidated immediately. Check token validity on every API request against your authorization server. Support token revocation endpoints for user logout and security incidents.
- _ Rate Limiting - Apply rate limiting to token-authenticated endpoints. Detect and block suspicious patterns (multiple failed attempts, unusual request volumes). Log token usage for security auditing. Implement account lockout after repeated authentication failures with invalid tokens.
Technical Implementation
Our bearer token generator uses PHP's random_bytes (CSPRNG) ensuring cryptographic randomness and unpredictability:
// Bearer Token Generation Algorithm (OAuth 2.0)
Algorithm: Cryptographically Secure Random Token Generation
// Step 1: Generate Random Bytes
byte_length = 32 (configurable: 16-128 bytes)
random_bytes = random_bytes(byte_length) // PHP CSPRNG
// Example: 32 bytes = 256 bits of entropy
// Step 2: Encode Based on Format
if (format == "base64url") then:
// OAuth 2.0 standard (RFC 4648 Section 5)
token = base64_encode(random_bytes)
token = strtr(token, '+/', '-_') // URL-safe chars
token = rtrim(token, '=') // Remove padding
// Example: yH3kT9mN5pQ2xR7jL4wV6sZ8aB1cD0eF
else if (format == "base64") then:
token = base64_encode(random_bytes)
// Example: yH3kT9mN5pQ2xR7+jL4wV/6sZ8aB1c==
else if (format == "hex") then:
token = bin2hex(random_bytes)
// Example: c87de4...93f (64 hex chars for 32 bytes)
else if (format == "alphanumeric") then:
charset = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
token = ''
for i = 0 to (byte_length * 2) do:
token += charset[random_int(0, 61)]
// Step 3: Calculate Metadata
entropy_bits = byte_length * 8 // 32 bytes = 256 bits
strength = assess_strength(entropy_bits)
// Usage in HTTP:
// Authorization: Bearer yH3kT9mN5pQ2xR7jL4wV6sZ8aB1cD0eF