DEV Community: Parveen Kumari

Postman Alternatives in 2026: 5 API Testing Tools Compared

Parveen Kumari — Sun, 28 Jun 2026 17:51:47 +0000

Postman has been the default API tool for developers for years. It's excellent for API exploration, debugging requests, and collaboration. But in 2026, software teams are looking beyond request collections.

Modern engineering teams want:

AI-generated test cases
Spec-driven automation
CI/CD integration
Contract testing
Self-hosted deployments
Better support for enterprise governance

If you're evaluating alternatives, here are five of the best API testing tools available today.

1. Shift Left API

Best for: AI-powered API test automation and enterprise DevOps teams.

Shift Left API is designed for teams that want to move beyond manually maintaining Postman collections. Instead of creating requests one by one, you import your OpenAPI, Swagger, or WSDL specification and automatically generate comprehensive API test suites.

Unlike traditional API clients, it focuses on complete API lifecycle automation.

Key Features

AI-generated API test cases
Import OpenAPI, Swagger and WSDL
REST, SOAP and GraphQL support
Self-hosted LLM support (Ollama, vLLM, LM Studio)
Cloud AI provider integrations
Endpoint management
API mocking
Test data generation
Test execution scheduling
CI/CD integrations
Coverage analytics
Contract validation
Enterprise security and compliance
Native GitHub Actions, Jenkins, Azure DevOps, GitLab, CircleCI
No-code test creation
AI-assisted maintenance
Detailed execution reports

Pros

Very little manual scripting
Excellent for large API portfolios
Enterprise-ready
Strong CI/CD integration
Self-hosted AI support for regulated industries

Cons

More automation-focused than manual API exploration
Best experience comes from having an OpenAPI specification available.

2. Insomnia

Best for: Developers who want a lightweight API client
Insomnia has become one of the most popular Postman alternatives because of its clean interface and Git-based workflow.

It supports REST, GraphQL and gRPC while keeping the user experience simple.

Key Features

REST
GraphQL
gRPC
Git Sync
Environment variables
Plugin ecosystem
Collection runner
Open-source core

Pros

Fast
Clean UI
Great developer experience
Git integration

Cons

Less focused on enterprise-scale automation
Limited AI capabilities

3. Bruno

**Best for: **Developers who want Git-first API collections

Bruno stores API collections directly on your filesystem instead of a cloud workspace.

This makes version control much easier and removes vendor lock-in.

Key Features

Offline-first
Git friendly
Plain text collections
REST support
Scripting
Collection runner

Pros
Open source

Lightweight
Excellent for Git workflows

Cons

Smaller ecosystem
Limited enterprise features

4. Hoppscotch

Best for: Free browser-based API testing

Hoppscotch is an open-source API client that runs directly in your browser.

It's ideal when you need a quick API request without installing desktop software.

Key Features

Browser-based
REST
GraphQL
WebSocket
Realtime collaboration
Environment management
Pros
Free
Fast
Easy to start

Cons

Less suited for enterprise automation
Smaller plugin ecosystem

5. ReadyAPI

Best for: Large QA organizations with existing SmartBear investments

ReadyAPI remains one of the strongest enterprise testing platforms, especially where SOAP services still play a significant role.

It includes functional testing, mocking, virtualization and performance testing.

Key Features

REST
SOAP
GraphQL
Load testing
Service virtualization
Security testing
Data-driven testing

Pros

Mature platform
Enterprise capabilities
Excellent SOAP support

Cons

Commercial licensing
Steeper learning curve
Manual test maintenance compared to newer AI-driven platforms

Comparison Table

Feature	Shift Left API	Insomnia	Bruno	Hoppscotch	ReadyAPI
REST	✅	✅	✅	✅	✅
SOAP	✅	❌	❌	❌	✅
GraphQL	✅	✅	Limited	✅	✅
AI Test Generation	✅	❌	❌	❌	Limited
OpenAPI Import	✅	✅	✅	✅	✅
API Mocking	✅	Limited	❌	Limited	✅
CI/CD Integration	✅	Limited	Limited	Limited	✅
Self-hosted AI	✅	❌	❌	❌	❌
Enterprise Compliance	✅	Limited	❌	❌	✅
No-code Automation	✅	❌	❌	❌	Partial

Which Tool Should You Choose?

Choose Shift Left API if:

You want AI to generate API tests
Your APIs are defined using OpenAPI or Swagger
You need enterprise automation
You work with REST, SOAP and GraphQL
You need CI/CD-ready automation
Your organization requires self-hosted AI

*Choose Insomnia if * you primarily need a developer-friendly API client.

Choose Bruno if Git-first workflows are your priority.

Choose Hoppscotch if you want a lightweight browser-based tool.

*Choose ReadyAPI if * your organization already relies on the SmartBear ecosystem and extensive SOAP testing.

Final Thoughts

Postman is still an excellent API client, but modern API testing increasingly demands automation, AI assistance, and seamless integration into CI/CD pipelines.

If your workflow still revolves around manually maintaining collections and scripts, it may be time to evaluate platforms that automate much of that work.

For teams adopting shift-left testing practices, AI-generated tests, contract validation, and spec-driven automation can significantly reduce maintenance effort while improving API quality.

What API testing tool are you using in 2026? Share your experience in the comments.

JWT Authentication, Explained by Actually Running One (No Setup)

Parveen Kumari — Sat, 16 May 2026 13:08:14 +0000

Decode a real JWT, exploit alg:none in 30 seconds, and learn exactly what to test in your own auth — all in your browser against a live sandbox

Most JWT tutorials show you a diagram and call it a day. This one is different: every example runs against a real sandbox API in your browser, so you can decode tokens, exploit alg: none, and watch a server actually reject (or accept) what you throw at it.

If you've ever signed off on a JWT implementation without being 100% sure what the library is doing under the hood — this is for you.

What a JWT actually is

A JWT (JSON Web Token, pronounced "jot") is a signed, self-contained string that carries claims about a user, used to authenticate requests.

Self-contained is the magic word. The server doesn't need to look up a session — the token itself has the user info plus a signature proving it hasn't been tampered with. The server just verifies the signature and trusts the claims.

** The three parts

A JWT is three Base64URL-encoded segments separated by dots:

eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjMiLCJuYW1lIjoiQWxpY2UifQ.sig_bytes_here
↑ header              ↑ payload                              ↑ signature

Decode the first two and you get JSON.

Header:

{ "alg": "HS256", "typ": "JWT" }

Payload (claims):

{
  "sub": "user-123",
  "email": "alice@example.com",
  "role": "admin",
  "iat": 1712345678,
  "exp": 1712349278
}

Signature: HMAC-SHA256(header.payload, secret) — or an RSA/ECDSA signature for asymmetric algorithms.

⚠️ Anyone can decode a JWT. The payload is signed, not encrypted. Never put secrets (passwords, credit-card numbers, anything you'd be sad to see in a log) in a JWT.

Standard claims (RFC 7519)

Claim	Meaning
`iss`	Issuer — who created the token
`sub`	Subject — who the token is about (user ID)
`aud`	Audience — who the token is for
`exp`	Expiration — Unix timestamp after which the token is invalid
`nbf`	Not Before — Unix timestamp before which it's invalid
`iat`	Issued At — when it was created
`jti`	JWT ID — unique identifier for revocation

Plus any custom claims your app needs: role, tenant_id, permissions, and so on.

Run a login and get a real token

Here's the login request — POST /auth/login against the public sandbox:

POST https://demo.totalshiftleft.ai/auth/login
Content-Type: application/json

{
  "email": "demo@totalshiftleft.ai",
  "password": "demo123"
}

Response:

{
  "access_token": "eyJhbGciOi...",
  "refresh_token": "eyJhbGciOi...",
  "expires_in": 900
}

Want to actually run it and see the real token come back?
👉 Run this live in your browser — no signup

Then call a protected endpoint with the token:

GET https://demo.totalshiftleft.ai/api/v1/me
Authorization: Bearer eyJhbGciOi...

Drop the Authorization header and you get a 401. That's the whole flow.

How the server verifies a token

On every request, the server runs through this checklist:

Read the Authorization: Bearer <token> header.
Split the token into header, payload, signature.
Check alg matches the expected algorithm — reject none explicitly.
Recompute the signature over header.payload using the secret/public key.
Compare the computed signature to the provided one — in constant time.
Parse the payload. Check exp is in the future and nbf is in the past.
Optionally check iss, aud, jti against a revocation list.
Only now treat the claims as trusted.

Skipping step 3 or 4 is the classic vulnerability — and several major libraries have shipped it.

Seven JWT vulnerabilities you should be able to test for

1. alg: none. Attacker changes the header to {"alg":"none"}, drops the signature, and forges any payload. Only works if the library accepts none. Reject it explicitly.

2. alg confusion (RS256 → HS256). Attacker flips alg from RS256 to HS256 and signs with the server's public key as if it were the HMAC secret. Naive libraries verify it as HMAC against the public key (which is, well, public) and accept it. Always pin the algorithm server-side. Never trust the header's alg.

3. Weak HMAC secrets. 8-character secrets can be brute-forced offline from a single valid token. Use ≥256 bits of entropy.

4. Long expirations. exp 30 days out means a stolen token is usable for 30 days. Access tokens should live ~15 minutes; long-lived refresh tokens do the rest.

5. No revocation. JWTs are stateless by design — which makes revocation hard. Mitigations: short expiry + refresh tokens, jti blacklist, or per-user "tokens issued before X are invalid" timestamps.

6. Storing JWTs in localStorage. Vulnerable to XSS. Use httpOnly, Secure, SameSite cookies for browser clients.

7. Generous clock skew. A 5-minute window is fine. A 24-hour window is a vulnerability.

What to actually test

If you're writing tests for a JWT-protected API — or QA-ing one — here's the checklist I actually use.

Happy paths

Login with valid creds → 200 with access_token, refresh_token, expires_in.
Protected endpoint with valid token → 200.
Token includes expected claims (sub, email, role).

Authentication negatives

No Authorization header → 401.
Wrong scheme (Basic instead of Bearer) → 401.
Malformed token (missing a segment) → 401.
Expired token (exp in the past) → 401 with a distinguishable code (e.g., TOKEN_EXPIRED).
Not-yet-valid token (nbf in the future) → 401.
Token signed with the wrong secret → 401.
alg: none token → 401. This is a security-critical test — most JWT libraries have shipped this bug at some point.
Tampered payload (modify a claim, keep the old signature) → 401.

Authorization negatives

Valid token with role: user hitting an admin endpoint → 403.
Valid token but tenant_id doesn't own the resource → 403 or 404 (document which — both are defensible).

Edge cases

Token issued by a different iss → 401.
Token with aud not matching this API → 401.
Token with a huge payload (10 KB of custom claims) → should work or 413.
Multiple Authorization headers → document the behavior (most stacks take the first).

Refresh flow

Valid refresh token → new access + refresh pair; old refresh token now invalid.
Re-using an old refresh token → 401 (detects token theft).
Refresh token after the user changes their password → 401. A password change should invalidate tokens.

Pen-tester checklist (steal this)

Copy the JWT, change alg to none, remove the signature — does it still work? If yes: critical bug.
If alg is RS256, try resigning with HS256 using the server's public key — does it work? If yes: critical bug.
Decode the payload. Anything that shouldn't be there (passwords, PII, internal IDs that leak architecture)? Report as data exposure.
Does the token include a jti? If not, revocation is likely not implemented.
Set the system clock past exp — does the token still work? Clock-skew vulnerability.

Try it yourself

Reading about JWTs is fine. Watching one fail validation in real time is better.

The full lesson — with a runnable login, a real protected endpoint, and the alg: none exploit live against a sandbox — is here, free, no signup:

👉 Learn JWT Authentication — runnable lesson

It's part of a free 32-lesson API testing course covering REST, GraphQL, SOAP, OAuth2, contract testing, and AI-assisted testing. Every lesson has a runnable example against a live sandbox: totalshiftleft.ai/learn.

What's your favorite JWT footgun in production? Drop it in the comments — I'm collecting them for the next post on refresh-token rotation patterns.