Validate JWT Token Signatures Instantly (Decode, Inspect & Verify)
Decode and validate JWT tokens instantly in your browser. Inspect header and payload claims, check expiry, and verify HMAC signatures (HS256/HS384/HS512). Free and private.
How to Use JWT Token Validator
How to Use the JWT Token Validator:
Paste Your Token: Copy your JWT (the three base64url-encoded parts separated by dots) and paste it into the token field. The header and payload decode instantly.
Inspect the Header: The header shows the signing algorithm (alg) and token type (typ). Click to expand or collapse the panel.
Inspect the Payload: The payload contains all claims such as sub, name, iat, exp, and custom claims. The tool highlights registered timing claims (iat, nbf, exp) in a dedicated section.
Check Expiry: The Expiry status card shows whether the token is still active or has expired. The exact exp timestamp is displayed in local time.
Verify the Signature (optional): For HMAC tokens (HS256, HS384, HS512), enter the secret key and click "Verify Signature". The tool uses the Web Crypto API in your browser — your secret never leaves your device.
Copy Claims: Use the Copy button on the Header or Payload panel to copy the decoded JSON for use in your application.
Notes:
- RS256, ES256, and other asymmetric algorithms require the public key; signature verification for these is not supported in the browser.
- Decoding works for any well-formed JWT regardless of algorithm.
- The tool does not validate audience (aud) or issuer (iss) — it only checks structural validity, expiry, and HMAC signature.
Frequently Asked Questions
Most Viewed Tools
TOTP Code Generator
Generate time-based one-time passwords from a TOTP secret key. Enter your base32 secret, choose a period and digit length, and get the current and next codes with a live countdown timer. Useful for testing and debugging 2FA integrations.
Use Tool →JSON to Zod Schema Generator
Generate Zod validation schema code from a JSON sample object. Infers z.string(), z.number(), z.boolean(), z.array(), z.object(), and z.null() types automatically. Handles nested objects, arrays of objects with optional field detection, and outputs copy-ready TypeScript with import and z.infer type alias.
Use Tool →JSONL / NDJSON Formatter
Format, validate, and inspect JSON Lines (JSONL) and NDJSON files. Validates each line individually, reports parse errors by line number, outputs compact JSONL or a pretty-print preview, and lets you download the cleaned file.
Use Tool →Secret and Credential Scanner
Scan pasted text, code, or config files for accidentally exposed API keys, tokens, passwords, and private keys. Detects 50+ secret types across AWS, GitHub, Stripe, OpenAI, and more — all client-side, nothing leaves your browser.
Use Tool →TLS Cipher Suite Checker
Check TLS protocol version compatibility and cipher suite strength ratings against current best practices. Supports IANA and OpenSSL cipher names — rates each suite as Strong, Weak, or Deprecated and explains why.
Use Tool →Password Entropy Calculator
Calculate the information-theoretic bit entropy of any password or API key. Detects character set pools automatically, shows the total number of possible combinations, and estimates crack time across five attack scenarios from rate-limited web logins to GPU cracking clusters.
Use Tool →TOML Config Validator
Validate TOML configuration file syntax and report errors with line numbers. Paste any TOML content — Cargo.toml, pyproject.toml, config.toml — and instantly see a green checkmark with key counts and structure stats, or a precise error message pointing to the exact line. Includes a collapsible JSON structure preview to confirm what was parsed.
Use Tool →Content Security Policy Generator
Build Content Security Policy headers interactively. Toggle directives like script-src, style-src, and img-src, select allowed source tokens, and add custom origins. Instantly outputs your CSP as an HTTP header, meta tag, Nginx directive, or Apache header.
Use Tool →Related API & Backend Tools
OpenAPI Spec Validator
Validate OpenAPI 2.0 (Swagger) and OpenAPI 3.0/3.1 specification files for compliance, missing required fields, unresolved $ref paths, and schema errors. Paste JSON or YAML or upload a file — errors and warnings are listed by path with severity levels and actionable fix suggestions. All validation runs entirely in your browser.
Use Tool →HTTP Request Headers Generator
Generate common HTTP request headers for authentication, content-type, caching, and security. Toggle each category, configure values, and copy the output as raw key-value pairs, JSON, fetch(), cURL, or axios.
Use Tool →Rate Limit Header Parser
Parse and visualize X-RateLimit headers from raw HTTP API responses. Paste response headers to instantly see your quota state — limit, remaining, used, and reset time — displayed as color-coded progress meters. Supports GitHub, OpenAI, Twitter/X, Shopify, and IETF standard rate limit headers.
Use Tool →GraphQL Variables Formatter
Format and validate GraphQL query variables JSON for use in queries and API clients. Paste your variables JSON alongside a GraphQL query to instantly format the JSON, validate that each variable matches its declared type, catch missing required variables, and highlight undeclared extras.
Use Tool →Postman to OpenAPI Converter
Convert Postman Collection v2.1 JSON to OpenAPI 3.0 specification format. Upload or paste your collection, and get a downloadable openapi.yaml or openapi.json with mapped paths, parameters, request bodies, and example responses.
Use Tool →API Tester
Test HTTP API endpoints directly in your browser. Make GET, POST, PUT, PATCH, and DELETE requests with custom headers and request bodies. View status codes, response headers, and pretty-printed JSON responses — all client-side, no server proxy.
Use Tool →CORS Header Generator
Build CORS configuration headers interactively for web servers and APIs. Set allowed origins, methods, request headers, credentials, and preflight cache duration — then copy the generated Access-Control headers or ready-to-paste code snippets for nginx, Express.js, Flask, and .NET.
Use Tool →REST Endpoint Documenter
Document a REST endpoint quickly by entering the URL, method, headers, and sample request/response. Generates formatted Markdown documentation and an example cURL command instantly.
Use Tool →Used in workflows
Share Your Feedback
Help us improve this tool by sharing your experience