JWT Tool – Token Decoder

JWT Tool — The Complete JWT Toolkit

A fast, privacy-first JWT toolkit for developers, security professionals, and learners. Decode, build, and verify JSON Web Tokens — completely offline.

JWT Decoder • Paste JWT or extract from clipboard instantly • View decoded header, payload, and signature • Real-time expiration countdown timer • Verify signatures (HS256, RS256, ES256 and more) • Automatic security vulnerability scanning • Load example tokens to learn JWT structure

JWT Builder • Create tokens with customizable claims • Quick templates: Auth, ID, Refresh tokens • Support for multiple algorithms (HMAC, RSA, ECDSA) • Set expiration with quick buttons (+1h, +1d, +7d) • Random secret key generator with strength indicator • Real-time token preview with color-coded sections

JWT Learning Guide • Structured tutorials from beginner to advanced • Learn JWT basics, structure, and algorithms • Interactive practice exercises • Track your learning progress

Developer Tools • Base64 Encoder/Decoder • Unix Timestamp Converter • Cryptographic Key Generator

Security Features • Detect alg=none vulnerability • Identify weak secrets and key confusion attacks • Check missing expiration and required claims

Token History • Save decoded and generated tokens • Mark favorites for quick access • Organize by date

Privacy First • No account required • No tracking or analytics • Works fully offline • All data stays on your device

Whether you're debugging authentication flows, building secure APIs, or learning JWT concepts, JWT Tool is your essential mobile companion.