Postman Alternatives 2025: Bruno vs Insomnia vs Thunder Client Comparison

Introduction: Beyond Postman

With Postman’s shift toward cloud-based features and pricing changes, developers are exploring lightweight, privacy-focused alternatives. This guide compares Bruno, Insomnia, and Thunder Client—three leading Postman (as discussed in API Testing Mastery: From REST to Contract Testing) alternatives for 2025.

Feature Comparison Matrix

Feature	Bruno	Insomnia	Thunder Client	Postman
Pricing	Free & Open Source	Free + Paid ($7/mo)	Free (VS Code)	Free + Paid ($12-49/mo)
Storage	Git-friendly (local files)	Local or Cloud	VS Code settings	Cloud-first
Collaboration	Git-based	Team workspaces (paid)	Limited	Advanced (paid)
Collections	Markdown files	JSON/YAML	JSON	Proprietary format
Scripting	JavaScript	JavaScript	JavaScript	JavaScript
Environment Variables	Yes	Yes	Yes	Yes
GraphQL Support	Yes	Excellent	Yes	Yes
OAuth 2.0	Yes	Yes	Yes	Yes
CLI/CI Integration	Yes (bruno-cli)	Yes (inso)	Limited	Yes (newman)
VS Code Integration	Extension	Extension	Native	Extension
Offline Mode	Full	Full	Full	Limited

Bruno: Git-Friendly API Client

Key Features

Git-native: Collections stored as plain text files
No account required: Fully offline
Open source: MIT licensed
Privacy-first: No data collection

Collection Structure

my-api/
├── environments/
│   ├── local.bru
│   ├── staging.bru
│   └── production.bru
├── users/
│   ├── get-users.bru
│   ├── create-user.bru
│   └── update-user.bru
└── bruno.json

Example Request File (.bru)

meta {
  name: Create User
  type: http
  seq: 2
}

post {
  url: {{baseUrl}}/api/users
  body: json
  auth: bearer
}

auth:bearer {
  token: {{authToken}}
}

body:json {
  {
    "username": "{{username}}",
    "email": "{{email}}",
    "role": "user"
  }
}

assert {
  res.status: eq 201
  res.body.id: isDefined
  res.body.username: eq {{username}}
}

script:pre-request {
  const timestamp = Date.now();
  bru.setVar("username", `user_${timestamp}`);
  bru.setVar("email", `user_${timestamp}@example.com`);
}

script:post-response {
  if (res.status === 201) {
    bru.setEnvVar("lastUserId", res.body.id);
  }
}

tests {
  test("Status code is 201", function() {
    expect(res.status).to.equal(201);
  });

  test("Response has user ID", function() {
    expect(res.body).to.have.property('id');
  });
}

CI/CD with Bruno CLI

# .github/workflows/api-tests.yml
name: API Tests

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v3

      - name: Setup Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '18'

      - name: Install Bruno CLI
        run: npm install -g @usebruno/cli

      - name: Run API Tests
        run: bru run --env production --output results.json

      - name: Upload Results
        uses: actions/upload-artifact@v3
        with:
          name: api-test-results
          path: results.json

Insomnia: Developer-Focused REST Client

Key Features

Design-first approach: OpenAPI/Swagger support
Plugin ecosystem: Extensible architecture
GraphQL excellence: Built-in GraphQL support
Team collaboration: Sync and share (paid)

Request Chaining

// Insomnia Request Script
const loginResponse = await insomnia.send('login-request');
const token = loginResponse.data.access_token;

// Set for subsequent requests
insomnia.environment.set('authToken', token);

Data Generation

// Using Faker.js in Insomnia
{
  "username": "{% faker 'internet', 'userName' %}",
  "email": "{% faker 'internet', 'email' %}",
  "firstName": "{% faker 'person', 'firstName' %}",
  "lastName": "{% faker 'person', 'lastName' %}",
  "age": {% faker 'number', 'int', 18, 80 %}
}

GraphQL Testing

# Insomnia GraphQL Request
query GetUserWithPosts($userId: ID!) {
  user(id: $userId) {
    id
    username
    email
    posts {
      id
      title
      content
      createdAt
    }
  }
}

# Variables
{
  "userId": "{{ userId }}"
}

CLI Integration (Inso)

# Export OpenAPI spec
inso export spec my-workspace --output openapi.yaml

# Run tests
inso run test my-workspace --env production

# Generate config
inso generate config my-workspace --type kubernetes

Thunder Client: VS Code Native

Key Features

VS Code native: No separate app needed
Lightweight: Minimal resource usage
Quick access: Integrated sidebar
Collections: Simple JSON format

Collection Example

{
  "client": "Thunder Client",
  "collectionName": "User Management API",
  "dateExported": "2025-10-04",
  "requests": [
    {
      "name": "Login",
      "method": "POST",
      "url": "{{baseUrl}}/auth/login",
      "body": {
        "type": "json",
        "raw": {
          "email": "user@example.com",
          "password": "password123"
        }
      },
      "tests": [
        {
          "type": "status-code",
          "value": 200
        },
        {
          "type": "json-query",
          "value": "json.token",
          "action": "setenv",
          "env": "authToken"
        }
      ]
    },
    {
      "name": "Get Profile",
      "method": "GET",
      "url": "{{baseUrl}}/users/me",
      "headers": [
        {
          "name": "Authorization",
          "value": "Bearer {{authToken}}"
        }
      ],
      "tests": [
        {
          "type": "status-code",
          "value": 200
        },
        {
          "type": "json-query",
          "value": "json.email",
          "action": "equal",
          "compare": "user@example.com"
        }
      ]
    }
  ]
}

Scripting

// Thunder Client Pre-request Script
tc.setVar("timestamp", Date.now());
tc.setVar("randomId", Math.floor(Math.random() * 10000));

// Thunder Client Test Script
if (tc.response.status === 200) {
  const data = tc.response.json;
  tc.setVar("userId", data.id);
  tc.test("User created successfully", data.id !== undefined);
}

Migration Strategies

From Postman to Bruno

# Export Postman collection (v2.1 JSON)
# In Postman (as discussed in [Postman: From Manual Testing to Full Automation](/blog/postman-from-manual-to-automation)): Collection -> Export -> v2.1

# Convert to Bruno format (using converter tool)
npm install -g postman-to-bruno
postman-to-bruno --input collection.json --output ./bruno-collection

# Initialize Git
cd bruno-collection
git init
git add .
git commit -m "Migrated from Postman"

From Postman to Insomnia

# In Insomnia:
# Dashboard -> Import -> Postman Collection
# Select your exported Postman JSON file

# Or use CLI
inso import postman collection.json

From Postman to Thunder Client

// Thunder Client supports direct Postman import
// VS Code Command Palette (Ctrl/Cmd + Shift + P)
// Thunder Client: Import Collection
// Select Postman JSON file

Decision Framework

Choose Bruno When:

Git-based workflow is essential
Privacy and offline-first are priorities
Team uses version control for everything
Open source is required
No account/cloud dependencies wanted

Choose Insomnia When:

Design-first API development (OpenAPI)
GraphQL testing is primary focus
Plugin ecosystem is valuable
Team collaboration with sync (paid)
Strong IDE-like features needed

Choose Thunder Client When:

VS Code is primary development environment
Lightweight solution preferred
Quick testing without app switching
Simple API testing needs
Free solution within VS Code

Stick with Postman When:

Advanced collaboration features required
Mock servers heavily used
API monitoring needed
Team already invested in Postman ecosystem
Budget allows for paid features

Best Practices for API Testing

1. Environment Management

// Separate environments for different stages
environments = {
  local: {
    baseUrl: "http://localhost:3000",
    apiKey: "local-dev-key"
  },
  staging: {
    baseUrl: "https://staging-api.example.com",
    apiKey: "{{STAGING_API_KEY}}" // From CI/CD (as discussed in [Testim & Mabl: AI-Powered Self-Healing Test Automation Platforms](/blog/testim-mabl-ai-self-healing-automation)) secrets
  },
  production: {
    baseUrl: "https://api.example.com",
    apiKey: "{{PROD_API_KEY}}" // From CI/CD secrets
  }
};

2. Reusable Auth Flows

// Pre-request script for token refresh
const tokenExpiry = pm.environment.get("tokenExpiry");
const now = Date.now();

if (!tokenExpiry || now >= tokenExpiry) {
  pm.sendRequest({
    url: pm.environment.get("authUrl"),
    method: 'POST',
    header: {
      'Content-Type': 'application/json'
    },
    body: {
      mode: 'raw',
      raw: JSON.stringify({
        username: pm.environment.get("username"),
        password: pm.environment.get("password")
      })
    }
  }, (err, res) => {
    if (!err && res.code === 200) {
      const token = res.json().access_token;
      const expiresIn = res.json().expires_in;

      pm.environment.set("authToken", token);
      pm.environment.set("tokenExpiry", now + (expiresIn * 1000));
    }
  });
}

3. Comprehensive Test Assertions

// Response validation
pm.test("Status code is 200", () => {
  pm.response.to.have.status(200);
});

pm.test("Response time is acceptable", () => {
  pm.expect(pm.response.responseTime).to.be.below(500);
});

pm.test("Response has correct structure", () => {
  const schema = {
    type: "object",
    required: ["id", "username", "email"],
    properties: {
      id: { type: "number" },
      username: { type: "string" },
      email: { type: "string", format: "email" }
    }
  };

  pm.response.to.have.jsonSchema(schema);
});

pm.test("Data integrity checks", () => {
  const data = pm.response.json();
  pm.expect(data.email).to.include("@");
  pm.expect(data.username).to.have.lengthOf.at.least(3);
});

Conclusion

The API testing landscape in 2025 offers excellent Postman alternatives, each with unique strengths. Bruno excels in Git-friendly workflows and privacy, Insomnia shines in design-first development and GraphQL, while Thunder Client provides seamless VS Code integration.

Recommendations:

For teams using Git extensively: Bruno
For GraphQL-heavy projects: Insomnia
For VS Code power users: Thunder Client
For enterprise collaboration: Postman (paid) or Insomnia Teams

All alternatives provide robust API testing capabilities with modern features, making migration from Postman smoother than ever. The choice depends on workflow preferences, collaboration needs, and privacy requirements rather than technical capabilities.