Best Open Source API Testing Tools for Developers: Hoppscotch vs Bruno vs Insomnia Compared

Best Open Source API Testing Tools for Developers: Hoppscotch vs Bruno vs Insomnia Compared

Postman has dominated API testing for years, but its move toward mandatory cloud accounts, telemetry, and paid team features pushed many developers to look elsewhere. The result is a healthy ecosystem of open source alternatives, each with a different philosophy about how API collections should be stored, shared, and executed.

Three tools come up most often in that conversation: Hoppscotch, Bruno, and Insomnia. They overlap in obvious ways—you send HTTP requests, inspect responses, and organize work into collections—but they diverge sharply on architecture. One runs in the browser, one treats your filesystem as the source of truth, and one has changed ownership and licensing in ways worth understanding before you commit.

Here’s how they actually compare.

Hoppscotch: The Browser-First Option

Hoppscotch started as a lightweight web app (originally called Postwoman) and has grown into a full API development platform. Its defining trait is that it runs primarily in the browser, which means zero installation and instant access from any machine.

Strengths:

• Instant onboarding. Open the web app, type a URL, hit send. There’s nothing to install.
• Broad protocol support. REST, GraphQL, WebSocket, SSE, Socket.IO, and MQTT are all handled natively—more than either competitor offers out of the box.
• Self-hostable. The entire platform can be deployed via Docker, which matters for teams with data residency requirements.
• Real-time tooling. The WebSocket and SSE interfaces are genuinely good, not afterthoughts.

Weaknesses:

• Browser limitations. Cross-origin restrictions can complicate requests to local or non-CORS-enabled endpoints unless you install the desktop app or a browser extension.
• Collection portability. Collections live in Hoppscotch’s cloud by default (or your self-hosted instance). You can import and export, but the filesystem isn’t the primary store, which makes Git-based workflows less natural.
• Cloud dependency for teams. Collaboration features lean on the hosted service unless you run your own backend.

Hoppscotch is licensed under MIT for the core, with some enterprise features under separate terms. For individual developers doing quick exploration or real-time protocol work, it’s hard to beat the friction-free start.

Bruno: The Git-Native Challenger

Bruno arrived in 2023 with a pointed critique of the status quo: API collections are code, so they should live in your repository, not someone else’s cloud. Every collection is stored as plain-text .bru files on your local filesystem.

Strengths:

• Filesystem-first, offline-only. No account, no sync, no telemetry. Your collections are files you can commit, diff, and review like any other code.
• Clean Git diffs. Because each request is a readable text file, pull requests show meaningful changes instead of opaque JSON blobs.
• Fast and lightweight. The desktop app (built on Electron) feels snappier than Insomnia in everyday use.
• Growing scripting support. Pre-request and post-response scripts use a JavaScript-like syntax, and the CLI (bru) supports running collections in CI pipelines.
• Open source under MIT. No dual licensing, no feature gates on the core product.

Weaknesses:

• Younger ecosystem. Fewer integrations, fewer community plugins, and less documentation than the alternatives.
• No built-in cloud sync. That’s the point, but teams that want managed sync need to solve it themselves (Git hosting, shared drives, etc.).
• Narrower protocol coverage. REST and GraphQL are solid; WebSocket and gRPC support have arrived but are less mature than Hoppscotch’s real-time tooling.

Bruno’s pitch resonates strongly with developers who already treat infrastructure as code. If your team reviews Terraform in pull requests, reviewing API collections the same way is a natural fit.

Insomnia: The Veteran With a Complicated History

Insomnia has been around since 2016 and was acquired by Kong in 2019. It’s the most feature-complete of the three, but its licensing and account policies have shifted in ways that alienated part of its user base.

Strengths:

• Mature feature set. Environment variables, request chaining, code generation, and a plugin ecosystem that the others can’t match.
• Polished UI. The interface is refined and handles large collections well.
• Design-first workflow. The OpenAPI editor and spec-driven request generation are genuinely useful for teams working from API specifications.
• Multiple storage options. Local vault, Git sync, and cloud sync are all available.

Weaknesses:

• Licensing friction. Insomnia moved to a proprietary license (with some open source components) and introduced account requirements for certain features. This is the single biggest reason developers cite for leaving.
• Mandatory sign-in pressure. Kong has walked back some of the most unpopular decisions, but the direction of travel has eroded trust.
• Heavier resource usage. It’s the slowest to launch and the most memory-hungry of the three.

If you’re already invested in Kong’s ecosystem or need the OpenAPI design tooling, Insomnia remains capable. If license purity matters to you, look elsewhere.

Head-to-Head Comparison

Feature	Hoppscotch	Bruno	Insomnia
License	MIT (core)	MIT	Proprietary
Storage	Cloud / self-hosted	Local filesystem	Local / cloud / Git
Account required	No (optional)	No	Yes for some features
Git-friendly	Moderate	Excellent	Moderate
Protocols	REST, GraphQL, WS, SSE, MQTT, Socket.IO	REST, GraphQL, gRPC, WS	REST, GraphQL, gRPC, WS
CLI / CI support	Yes	Yes (bru)	Yes (inso)
Desktop app	Yes	Yes	Yes
Best for	Quick testing, real-time protocols	Git-centric teams	Spec-driven, feature-heavy workflows

Which Should You Choose?

The honest answer depends on what you value most:

• Choose Hoppscotch if you want to start testing in seconds, work heavily with WebSockets or other real-time protocols, or need a self-hostable platform for a team.
• Choose Bruno if your team lives in Git, cares about license purity, and wants API collections reviewed alongside the code they test.
• Choose Insomnia if you need the deepest feature set, OpenAPI design tooling, or you’re already embedded in Kong’s ecosystem and can accept the licensing terms.

Many developers end up using more than one. Hoppscotch for quick browser-based checks, Bruno for the collections that live in the repo. That’s a perfectly reasonable setup—these tools aren’t mutually exclusive.

The Takeaway

The API testing market has matured past the point where one tool needs to win. Hoppscotch, Bruno, and Insomnia each represent a distinct answer to the question of where your API work should live: in the browser, in your repository, or in a managed platform. Bruno’s Git-native model has gained the most momentum among developers who want their tooling to behave like code, while Hoppscotch wins on accessibility and real-time protocol support. Insomnia still has the deepest feature set, but its licensing decisions have cost it goodwill that’s unlikely to return soon.

Try all three against a real project before committing. The migration cost between them is low—they all import common formats like OpenAPI and Postman collections—so the decision is reversible. What matters is picking the storage and collaboration model that matches how your team already works.