JSON Web Token FAQs and debug
2 min readApr 19, 2021
What is JSON Web Token (JWT)?
A compact, URL-safe means of representing claims to be transferred between two parties.
How does JWT look like?
In its compact form, JSON Web Tokens consist of three parts separated by dots (.), which are:
- Header
- Payload
- Signature
Therefore, a JWT typically looks like the following. xxxxx.yyyyy.zzzzz
Is JWT for authentication?
No. Since JWT process start only after successful authentication, JWT is only for authorization.
What are advantages of JWT?
- No backend store — As server encodes all the data about the grant into the token itself, No data stored at server except secret
- No Session to Manage (stateless) — JWT is a self-contained token (and gets stored at client side,) server does not need to keeps track of it
- Supports scaling — As no session tracked, single point of failure (SPOF) of ‘shared session cache’ / session affinity avoided in multiple server instance
- More compact — As JSON is less verbose than XML so when encoded it’s more compact as compaired to simple web tokens (SWTs) and Security Assertion Markup Language (SAML) tokens
- More secure -Even though it can be read by anybody but it can not be tampered. JWT supports varius algoriths that supports public/private key pair, symmetrically signed, so on
- Portable — A single token can be used with multiple backends. ideal in micro service environment with 2/3 legged token
- Decoupled/Decentralized — The token can be generated anywhere. Authorization can happen on the resource server, or easily separated into its own server
What are disadvantages of JWT?
- Can’t easily revoke an access token, so they normally are granted with short expiry and the revocation is handled at the refresh token
- Unless In secure communication, a token can be stolen and misused. Https communication recommended
