Postman vs Insomnia vs Bruno: The Best API Testing Tool for Modern Developers

If you’re a developer who has written a single line of code that calls an external service, you’ve likely lived inside a REST client. Postman has dominated this space for over a decade, but the landscape is shifting. With over 30 million developers using Postman annually, it remains the default choice. However, a wave of lightweight, open-source alternatives—led by Insomnia and the newer Bruno—are challenging that hegemony.

The question isn’t simply “Which is the best?” It’s “Which fits your specific workflow?” The answer depends on where you sit: Are you a solo developer on a MacBook, a QA engineer in a corporate enterprise, or a DevOps engineer who wants API collections committed to Git?

We tested all three tools across performance, collaboration, and developer experience to give you a clear, unbiased breakdown.

The Contenders at a Glance

Before diving into nuances, let’s establish the baseline architecture of each tool.

Postman is the industry veteran. It functions as a cloud-based ecosystem, requiring an account for most features. It offers a native app, but the heart of the tool is its sync engine and cloud workspace.

Insomnia (owned by Kong) is the middle ground. It is a desktop-first application that offers cloud sync as a premium feature. It is widely respected for its clean interface and GraphQL support.

Bruno is the disruptor. It is an open-source tool (MIT license) that stores your API collections directly on your file system as plain text files (using a markup language called Bru). There is no cloud sync, no account required, and no data leaves your machine.

Performance and Resource Usage

This is the first major differentiator. Postman has a reputation for being heavy. Built on Electron, it routinely consumes 500MB to 1GB of RAM, especially with multiple tabs open. On a standard 8GB RAM development machine, running Postman alongside a browser and an IDE can cause noticeable lag.

Insomnia is also Electron-based, which historically carried similar bloat. However, recent versions (particularly Insomnia 2023+ and the 2024 redesign) have optimized memory usage significantly. It is noticeably snappier than Postman, though it still gets sluggish with large response bodies.

Bruno takes a different technical route. It is built on Electron as well, but because it does not need to maintain a persistent connection to a cloud backend for syncing, the local processing is much faster. In our tests, Bruno opened complex collections in under two seconds, while Postman took over five seconds on the same cold start. Bruno’s rendering of massive JSON payloads is also smoother, as it doesn’t have the overhead of background telemetry and sync watchers.

Verdict: If you want speed and low resource drain, Bruno wins. If you want a balance of features and acceptable performance, Insomnia is fine. Postman is the heaviest.

The Git-First Workflow (Bruno’s Superpower)

The most significant philosophical shift in API testing is the move toward “version-controlled APIs.” In the modern DevOps world, we treat code, infrastructure, and configuration as code. Why not API collections?

Postman handles this via a paid “Git Sync” feature (available on Professional and Enterprise plans). Without paying, you are locked into Postman’s cloud, and your collections live in their database. If you want to review a teammate’s changes via a Pull Request, you have to export JSON files, compare them manually, or pay for the feature.

Bruno solves this elegantly by design. Every request, every environment variable, and every test script is a plain-text file. You store the entire collection folder in your GitHub or GitLab repository. When you want to change a request, you edit the file, commit it, and open a PR. Your code reviewer can see the exact diff in the API request—no proprietary export/import cycle required.

This is a massive win for teams that value code review. It also means there is zero vendor lock-in. If Bruno disappears tomorrow, you still have your text files.

Insomnia sits in the middle. It offers Git Sync as a paid feature via Insomnia Plus, but the implementation is clunkier than Bruno’s native file structure.

Verdict: For teams using Git (which is almost everyone), Bruno is the clear winner for collaboration.

Testing Capabilities and Scripting

When you move beyond simple GET requests, you need scripting support.

Postman has the most mature scripting environment. It uses a sandboxed JavaScript engine that allows you to write pre-request scripts and post-response tests. The pm object (e.g., pm.test(), pm.expect()) is powerful and well-documented. It supports environment variables, data-driven testing (via CSV/JSON), and the Newman CLI runner for CI/CD pipelines. If you are building complex automated test suites, Postman’s ecosystem is the most robust.

Insomnia offers scripting through a plugin system and supports JavaScript in the “Pre-request” and “Response” tabs. It has native support for GraphQL, which is a significant advantage if you work heavily with that query language. However, its test assertions are less intuitive than Postman’s, and the CI integration requires the Inso CLI, which has had a rocky history of bugs.

Bruno has been rapidly catching up. It supports JavaScript test scripts using the expect() and test() methods, which are syntactically similar to Jest. It supports assertions on status codes, headers, and response bodies. It also has a built-in CLI runner (Bruno CLI) for CI pipelines. However, it lacks the deep enterprise features of Postman, such as the built-in API documentation generation and the monitoring service.

Verdict: For complex enterprise testing suites, Postman wins. For simple to intermediate scripted tests, Bruno is more than sufficient and offers cleaner syntax.

Security and Data Privacy

This is a critical consideration for developers working with sensitive data (e.g., healthcare, finance, government).

Postman has faced scrutiny regarding data privacy. When you sign in, your collections (which may contain API keys or sensitive payloads) are stored on their cloud servers. In 2023, Postman updated its terms to allow “aggregate, anonymized” data usage for AI training, which caused a stir in the developer community. While you can disable telemetry, the default is data collection.

Bruno is fully offline. There is no account, no cloud, and no telemetry. Your API keys stay in your local files. If you commit them to a private repo, you control the security. This is the primary reason many security-conscious developers are switching.

Insomnia offers a hybrid approach. The free version is local, but features like sync require cloud storage. Kong has a solid privacy policy, but it still requires network trust if you use their sync features.

Verdict: Bruno is the only tool that guarantees zero data leaves your machine.

User Interface and Learning Curve

Postman’s UI has become cluttered over the years. The navigation is dense, with numerous buttons, a sidebar for collections, a separate sidebar for environments, and constant prompts to try paid features. For a beginner, this is overwhelming.

Insomnia is the sleekest of the three. Its UI is minimalist, with a focus on the request pane. It is generally considered the easiest to pick up if you are coming from tools like curl or HTTPie.

Bruno is functional but less polished. It looks a bit like a lightweight IDE. The interface is intuitive—a left sidebar for collections and a central pane for requests—but it lacks the visual gloss of Insomnia. However, because it’s open source, the community is actively improving it.

Verdict: Insomnia wins for pure UI aesthetics. Bruno wins for simplicity. Postman wins for feature discovery but loses on usability.

The Verdict: Which Should You Use?

We can break this down into three distinct user profiles.

Choose Postman if:

  • You work in an enterprise environment that requires centralized collaboration and role-based access.
  • You need advanced features like API monitoring, documentation portals, and mock servers.
  • You are heavily invested in the Newman CLI and need data-driven testing at scale.
  • You are willing to pay for the Professional tier to get Git sync and advanced security.

Choose Insomnia if:

  • You primarily work with GraphQL APIs.
  • You want a clean, distraction-free UI.
  • You are a solo developer or small team that doesn’t need heavy collaboration features.
  • You want a middle ground between Postman’s bloat and Bruno’s bare-bones approach.

Choose Bruno if:

  • You believe in “API as Code” and want collections in your Git repository.
  • You are concerned about data privacy and want a fully offline tool.
  • You are a solo developer or a team that uses Git for code review.
  • You want a fast, lightweight tool that doesn’t eat your RAM.
  • You dislike vendor lock-in and want an open-source solution.

Final Takeaway

The era of the “all-in-one” API client is fading. Postman is still the most powerful, but it is becoming a platform—which brings complexity and cost. Insomnia remains a great middle option, but its future roadmap is uncertain under Kong’s management.

Bruno represents a paradigm shift back to developer fundamentals: local files, Git, and simplicity. It is not yet a full replacement for Postman in enterprise scenarios, but for the modern developer who values speed, security, and version control, Bruno is the most forward-looking choice. If you haven’t tried it yet, create a collection, save it to a repo, and experience the freedom of an API client that doesn’t require you to sign in.