Postman vs Insomnia vs Thunder Client: Which API Client Is Best in 2025
Three tools dominate the conversation when developers argue about API clients: Postman, Insomnia, and Thunder Client. Each has a loyal following, and each has changed significantly over the past two years—through acquisitions, pricing shifts, and feature pivots that have pushed some users to switch.
This comparison looks at where all three stand in 2025: what they cost, how they perform, and which types of developers they actually serve best.
The Quick Verdict
- Postman remains the most feature-complete option, with the deepest collaboration, testing, and documentation tooling. It’s also the heaviest and the most expensive at scale.
- Insomnia offers a cleaner, faster experience with strong GraphQL and gRPC support. Since Kong acquired it in 2019, its free tier has narrowed, which frustrates some longtime users.
- Thunder Client is a lightweight VS Code extension that keeps you inside your editor. It’s ideal for quick requests and small teams, but it lacks the collaboration depth of the other two.
Postman: The Industry Standard, for Better and Worse
Postman started in 2012 as a Chrome extension and grew into a full API platform. Today it’s used by millions of developers and the overwhelming majority of Fortune 500 companies, according to Postman’s own reporting.
What works well:
- Collections and workspaces make it easy to organize requests, share them with a team, and keep environments (dev, staging, prod) in sync.
- Automated testing with JavaScript assertions is mature. You can chain requests, run collections via the Collection Runner or Newman (the CLI), and wire results into CI/CD pipelines.
- Mock servers, documentation generation, and API monitoring are built in, which matters if you’re managing an API others depend on.
- The ecosystem is huge. Tutorials, integrations, and community answers exist for nearly every problem you’ll hit.
Where it falls short:
- Resource usage. Postman is an Electron app, and it feels like one. On older machines or with large collections, startup and search can lag.
- Pricing. The free tier is generous for individuals, but team plans get costly fast. Postman’s pricing has shifted repeatedly, and the move toward “Postman API Platform” branding means features that were once free now sit behind paid tiers.
- Account requirements. Postman increasingly pushes you to sign in and sync to the cloud, which is a nonstarter for some security-conscious teams.
Insomnia: Clean, Fast, and GraphQL-Friendly
Insomnia was built by Gregory Schier in 2016 as a reaction to Postman’s growing complexity. Kong acquired it in 2019, and it has since been folded into Kong’s broader API tooling strategy.
What works well:
- Interface. Insomnia’s UI is noticeably cleaner and less cluttered than Postman’s. If you just want to fire off a request, it’s faster to get there.
- GraphQL and gRPC. Insomnia’s GraphQL support—schema introspection, autocomplete, query editing—is arguably the best of the three. gRPC support is also solid.
- Design-first workflow. Insomnia leans into OpenAPI spec editing, letting you design an API and generate requests from the spec.
- Plugin ecosystem. Node.js-based plugins let you extend request/response handling in ways Postman doesn’t easily allow.
Where it falls short:
- Free tier limitations. Kong has moved several features—like Git sync and some collaboration tools—behind paid plans. For solo developers the free tier still works, but teams may hit walls.
- Collaboration. It’s improved, but it still trails Postman for multi-user workflows, shared environments, and permission controls.
- Testing. Insomnia can run test suites, but the tooling is less mature than Postman’s, especially for CI integration.
Thunder Client: Lightweight and Editor-Native
Thunder Client launched in 2020 as a VS Code extension and grew quickly by targeting developers who didn’t want to leave their editor. It now has millions of installs on the VS Code Marketplace.
What works well:
- Zero context switching. Requests, responses, and code all live in the same window. For developers who live in VS Code, this alone is a major productivity win.
- Speed. It’s far lighter than Postman or Insomnia. Startup is instant, and it doesn’t compete for RAM with your editor’s other extensions.
- Simple pricing. A free tier covers most individual needs, and the paid “Ultra” tier is inexpensive compared to Postman’s team plans.
- Git-friendly. Collections are stored as plain files, which makes version control straightforward.
Where it falls short:
- VS Code only. If your team uses JetBrains IDEs, Vim, or anything else, Thunder Client is out.
- Feature depth. No mock servers, limited scripting, and a thinner testing story. It’s a request runner, not an API platform.
- Collaboration. Team features exist but are basic. For a five-person startup it’s fine; for a fifty-person platform team, it isn’t.
Head-to-Head Comparison
| Feature | Postman | Insomnia | Thunder Client |
|---|---|---|---|
| Platform | Desktop app, web | Desktop app | VS Code extension |
| Free tier | Generous for solo | Limited | Generous |
| Team pricing | Expensive at scale | Mid-range | Inexpensive |
| GraphQL | Good | Excellent | Basic |
| gRPC | Supported | Strong | Limited |
| Automated testing | Best-in-class | Moderate | Basic |
| CI/CD integration | Newman, CLI | Limited | Limited |
| Resource usage | Heavy | Moderate | Very light |
| Collaboration | Best-in-class | Moderate | Basic |
How to Choose
The right pick depends less on features than on your context.
Choose Postman if: You work on a team that needs shared collections, automated tests, documentation, and CI integration. The cost is real, but so is the time saved on coordination.
Choose Insomnia if: You want a fast, clean client with strong GraphQL or gRPC support, and you’re comfortable with its paid tiers for team features. It’s a good middle ground.
Choose Thunder Client if: You’re a solo developer or part of a small VS Code-centric team, and you mostly need to send requests and inspect responses without leaving your editor.
Many developers use more than one. It’s common to keep Thunder Client for daily poking and Postman for shared team collections. There’s no rule that says you have to commit to a single tool.
The Bottom Line
In 2025, Postman is still the most capable API client, but “most capable” comes with weight, cost, and cloud lock-in. Insomnia is the better-designed tool for individual workflows, particularly around GraphQL, though Kong’s monetization has narrowed its free tier. Thunder Client wins on speed and simplicity but stays inside VS Code and doesn’t pretend to be a platform.
If you’re evaluating for a team, start with the collaboration and CI requirements—those usually decide the choice before feature checklists do. If you’re evaluating for yourself, install all three. They’re free to try, and the one that fits your hands is the one you’ll actually keep using.