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

If you’ve written a single line of backend code in the last decade, you’ve likely hit Ctrl+Enter in Postman to fire off a test request. For years, Postman was the undisputed king of API development—a tool so ubiquitous that “Postman” became a verb. But the landscape has shifted. Developers are increasingly frustrated by bloated UIs, forced cloud sync, and licensing changes. Enter Insomnia, a long-time challenger with a loyal following, and Bruno, a relative newcomer that has taken the open-source community by storm.

According to the 2023 Stack Overflow Developer Survey, over 21% of professional developers use Postman, making it the most popular API tool by far. However, the same survey noted a growing trend toward lightweight, Git-friendly alternatives. So, which tool actually deserves a spot in your daily workflow? This isn’t about which one has the prettiest logo; it’s about performance, privacy, collaboration, and whether the tool respects your time and your codebase.

In this deep dive, we’ll compare Postman, Insomnia, and Bruno across the metrics that matter most to modern developers: performance, data storage, collaboration, and extensibility.

The Contenders at a Glance

Before we dive into the nitty-gritty, let’s set the stage with a high-level overview of each tool’s philosophy.

  • Postman: The enterprise heavyweight. It’s a full-featured API platform that now includes API design, mocking, documentation, and monitoring. It is cloud-first, requiring an account for most features.
  • Insomnia: The developer’s favorite for those who want a polished GUI without the enterprise bloat. It offers a hybrid model—local data with optional cloud sync—and has a strong focus on GraphQL.
  • Bruno: The radical upstart. Bruno is a fully offline, open-source tool that stores your API collections as plain text files (using a markup language called Bru). It treats your API tests like code, meaning you can version them with Git.

Performance and Resource Usage

Let’s address the elephant in the room: Electron apps are memory hogs. All three of these tools are built on Electron, so none of them are truly “lightweight” compared to terminal-based tools like curl or httpie. However, there are significant differences in how they manage resources.

Postman has a reputation for being the heaviest. A fresh install with no collections can easily consume 400–600 MB of RAM. If you have a large workspace with many tabs open, it’s not uncommon to see it cross the 1 GB threshold. This is due to its extensive feature set—the UI is rendering a lot of background processes for cloud sync, update checks, and telemetry. On a 16 GB MacBook Pro, running Postman alongside Chrome and an IDE can cause noticeable fan spin-up.

Insomnia is noticeably leaner. It typically sits in the 200–300 MB range. The interface feels snappier, and switching between requests is nearly instantaneous. Insomnia’s decision to keep the core client local and only sync when requested makes it feel more responsive than Postman’s always-cloud approach.

Bruno is the leanest of the three. Because it doesn’t have any cloud backend, there is no background sync process eating up CPU cycles. It generally uses around 150–200 MB of RAM. More importantly, the startup time is significantly faster. While Postman can take 5–10 seconds to fully load on a standard SSD, Bruno feels like a native app, booting in under two seconds.

The Verdict: If you are on a resource-constrained machine or hate waiting for splash screens, Bruno wins outright. If you need the full feature set but want a break from Postman’s bloat, Insomnia is the sweet spot.

Data Storage and Git Friendliness

This is where the philosophical divide becomes stark. How your API collections are stored dictates how you collaborate, review, and deploy.

Postman stores everything in the cloud (unless you use the deprecated offline version). Collections are saved to Postman’s servers, and while you can export them as JSON files, the workflow is clunky. You cannot easily use git diff to see what changed in a collection. This forces you to rely on Postman’s built-in versioning, which is locked behind a paywall for team workspaces. For developers who love pull requests and code reviews, Postman is an anti-pattern.

Insomnia offers a hybrid approach. By default, data is stored locally in a SQLite database. You can enable Insomnia Sync (cloud) or, crucially, you can use the “Git Sync” feature. This allows you to store your collections as JSON files in a repository. However, the JSON format is verbose and difficult to read in a text editor. While you can review a Git diff, it’s not pretty. It’s a functional solution, but not an elegant one.

Bruno flips the script entirely. Collections are stored as plain-text .bru files. Here is what a simple GET request looks like in Bruno:

meta {
  name: Get User
  type: http
  seq: 1
}

get {
  url: https://api.example.com/users/1
  body: none
  auth: none
}

This is beautiful for developers. You can open a .bru file in any text editor, read it instantly, and see exactly what the request does. When a teammate changes the URL or adds a header, your standard Git workflow (branching, pull requests, merge conflicts) just works. There is no proprietary format to parse.

The Verdict: Bruno is the undisputed champion for teams that live in Git. Insomnia is a decent middle ground, but Postman’s cloud-lock-in is a major drawback for modern, code-first teams.

Collaboration and Team Features

While Git is great for code, non-developer stakeholders (like QA testers or product managers) often prefer a visual interface for collaboration.

Postman is the gold standard here. Its team workspaces allow real-time collaboration. You can see who is online, leave comments on specific requests, and share collections via a simple link. The “Postman API” allows you to programmatically manage your workspace, and integrations with CI/CD pipelines (like Jenkins and GitHub Actions) are mature. If you work in a large enterprise with non-technical testers, Postman’s collaboration tools are unmatched.

Insomnia offers collaboration through its Insomnia Cloud (now part of Kong). You can create a “Design” document and share it with your team. However, the real-time presence features are less polished than Postman. It feels more like a developer-centric tool where collaboration is an afterthought, not the core experience.

Bruno does not have any cloud collaboration features—by design. The philosophy is that you should use Git for collaboration. For a team of senior developers, this is liberating. No more “who changed the collection?” mysteries. For a team with less technical members, this is a barrier to entry. If you want to share a collection with a QA analyst who doesn’t use Git, you have to export a file or teach them how to clone a repo.

The Verdict: If you need real-time visual collaboration, Postman wins. If you are a senior engineering team that lives in the terminal and GitHub, Bruno’s lack of cloud features is a feature, not a bug.

Extensibility and Scripting

Testing isn’t just about sending requests; it’s about validating responses. All three tools support pre-request scripts and post-response tests, but the languages and execution environments differ.

Postman uses JavaScript (Node.js sandbox). It has a robust library of built-in snippets (like pm.test, pm.expect, and chai assertions). The scripting engine is powerful, allowing for complex workflows, data-driven testing, and even integration with external libraries. However, the sandbox is notoriously strict—you cannot use require() to load arbitrary npm packages easily.

Insomnia also uses JavaScript but with a slightly different API. It relies on the insomnia.test object. The templating engine (Nunjucks) is excellent for dynamic variables (e.g., generating a timestamp or parsing a previous response). It’s a bit more flexible than Postman in terms of importing libraries, but the documentation is not as extensive.

Bruno uses JavaScript as well, but its scripting model is newer. It supports an assert pattern and allows for dynamic variables using a similar syntax to Insomnia. However, because Bruno is so new, the community snippets and documentation are sparse. If you need to write complex test suites with lots of edge cases, you might find yourself writing more boilerplate in Bruno than you would in Postman.

The Verdict: Postman has the richest ecosystem and documentation for scripting. Bruno has the potential to catch up, but it’s currently a laggard for advanced test automation.

Security and Privacy

In a world of supply chain attacks and data leaks, where your API data lives matters.

Postman requires you to log in to use the desktop app. While you can use it for free, your data passes through Postman’s servers. For companies dealing with HIPAA or PCI compliance, sending API requests (which may contain sensitive data) through a third-party proxy is a red flag. Postman also had a notable security incident in 2023 where a malware distribution campaign used fake Postman sites to steal credentials.

Insomnia allows 100% local usage. You can use it without an account, and your data never leaves your machine unless you opt into cloud sync. This is a significant privacy win.

Bruno is the most secure by default. There is no cloud, no account, and no telemetry. Your requests never leave your computer. For security-conscious developers or those working on air-gapped networks, Bruno is the only viable choice of the three.

The Verdict: Bruno for absolute privacy, Insomnia for a balance, and Postman for those who trust the cloud.

The Final Takeaway

So, which tool should you use? The answer depends entirely on your context.

  • Choose Postman if you work in a large enterprise with mixed technical skill levels, need built-in API documentation and monitoring, and don’t mind the resource drain or the cloud dependency. It is a Swiss Army knife, but it’s a heavy one.
  • Choose Insomnia if you are a solo developer or work in a small team that wants a polished GUI, excellent GraphQL support, and the flexibility to sync via Git or the cloud without the bloat of Postman.
  • Choose Bruno if you are a developer-first purist. If you want your API tests to live in the same repository as your code, be reviewed in the same pull requests, and run without any network overhead, Bruno is the future. It forces a discipline that Postman and Insomnia simply cannot offer.

The trend in software development is moving toward local-first, Git-native tools (think VS Code, Obsidian, and now Bruno). While Postman still holds the market share, tools like Bruno are gaining traction because they respect the developer’s workflow rather than forcing them into a proprietary ecosystem.

My recommendation? Try Bruno for your next side project. The lack of cloud sync might feel jarring at first, but the moment you do a git diff on an API collection and see a clean, readable change, you’ll realize that the “Postman way” is outdated. For modern developers, your API tests should be code—and Bruno is the only tool on this list that treats them that way.