Browser-only JWT cryptography
Sealkey
Forge production JWT secrets and key pairs, then sign and verify tokens without leaving your browser.
Quick HMAC forge
HS256 · 256-bitK7mQ2pR9vX4nL8wY3cF6hJ1aS5dG0uB2eT9iO4zP7xN0
bits0
Shannon H0
network 100% client-side Web Crypto API Symmetric + asymmetric Sign · decode · verify
Built for teams that outgrew basic secret generators
Sealkey packs the workflows you usually jump between three tools for into one private lab.
HMAC + asymmetric keys
HS256-512 secrets plus RSA, ECDSA, and Ed25519 key pairs with PEM and JWKS export.
Sign, decode, verify
Full JWT playground in one place. Inspect claims, mint tokens, and check signatures locally.
Entropy analyzer
Shannon entropy, charset coverage, and strength guidance before you ship a secret.
Rotation planner
Kid-based cutover checklist with a grace window so old tokens keep working.
Why teams switch to Sealkey
Typical free generators
Sealkey
HMAC secrets only
HMAC + RSA / EC / Ed25519 + JWKS
Separate decoder page
Decode, sign, and verify in one lab
Basic length presets
Live entropy + charset + batch export
No rotation guidance
Kid rotation plan with grace period
Few code samples
8 languages + dotenv / K8s / shell exports
Ready to forge stronger JWT keys?
Open the lab, generate material with Web Crypto, and copy env-ready exports in seconds.