Thunder Client: Test APIs Without Leaving VS Code

The Context-Switch Tax

Every time you leave VS Code to test an API — opening Postman, waiting for it to load, digging through collections — you lose flow. Small interruptions compound fast over a workday.

Thunder Client brings API testing into the editor itself.

Install in 30 Seconds

1. Open VS Code Extensions (⇧⌘X) 2. Search for **Thunder Client** 3. Click Install

A lightning bolt icon appears in your sidebar. You're done.

Making Your First Request

Click the sidebar icon → **New Request**


Method: GET
URL:    https://api.github.com/users/rajeev00723

Headers: Accept: application/vnd.github.v3+json

Hit **Send**. The JSON response appears in the panel below, syntax-highlighted and collapsible.

What It Does Well

**Collections** — organize requests by project or service, just like Postman. Share the collection JSON in your repo so the whole team has the same test suite.

**Environment variables** — define `{{BASE_URL}}`, `{{AUTH_TOKEN}}` etc. per environment (local, staging, prod) and switch with a dropdown.


# .env.local equivalent in Thunder Client
BASE_URL = http://localhost:3000
AUTH_TOKEN = eyJhbGci...

# Used in requests as: {{BASE_URL}}/api/users Authorization: Bearer {{AUTH_TOKEN}}

**Tests** — write assertions directly on responses:

javascript
// Thunder Client test tab
tc.test("Status is 200", () => {
  tc.expect(response.status).toBe(200)
})

tc.test("User has name", () => { tc.expect(response.json.name).toBeDefined() })

Limitations to Know

Thunder Client is built for REST. If you're working heavily with GraphQL subscriptions or need advanced OAuth flows, Postman or Insomnia still have the edge. For everyday REST debugging — endpoints, headers, auth tokens, JSON payloads — Thunder Client handles it completely.

Takeaway

If you're already in VS Code, there's no reason to open a separate API client for routine testing. Thunder Client removes the friction without removing the features that matter.