Why the World Needs a Faster, Lighter API Tool

APIs are the backbone of modern software. Developers use API tools every day to build, test, and debug the products that power our digital world. But many of today’s most popular tools—like Postman, Insomnia, and Apidog—have become bloated, slow, and demanding on system resources.
 
As development teams push for faster feedback loops and cleaner workflows, it’s clear: we need a better alternative. One that’s built for speed, simplicity, and focus.
 
That’s exactly why we built Sparrow.

In this post, we compare Sparrow to leading API clients through a hands-on performance and usability study. From startup speed to memory usage, the findings make one thing clear—a faster, lighter API tool isn’t just nice to have anymore. It’s essential.
 
How We Evaluated the Tools

We tested five tools—Sparrow, Postman, Insomnia, Apidog, and Bruno—using a standardized methodology. Each was installed on the same Windows 11 system, running on an Intel Core i7 processor with 16 GB of RAM. To keep things fair and realistic, we tested each tool in two ways:

• Cold start: launching the app after restarting the computer
• Warm start: opening the app again while it’s still in memory

We used five public APIs that developers often test with:

• JSONPlaceholder (POST)
• Reqres (GET)
• DummyJSON (GET)
• Dog API (GET)
• HTTPBin (POST)

For each tool, we measured:

• How fast it responded to API calls
• How much memory (RAM) it used
• How quickly it launched
• How well it worked without internet
• How smooth the overall experience was for developers

Storage and Installation Footprint

One of the first places Sparrow stands out is in its size. While most competitors require significant disk space, Sparrow’s download package is just over 21 MB, and its installed size is under 50 MB. In contrast, Postman installs at around 135 MB, Insomnia weighs in at 160 MB, and Bruno occupies 400 MB. Apidog, the most bloated of the lot, reaches a staggering 819 MB when fully installed. For developers who prioritize lean tools and fast installations, Sparrow clearly sets itself apart.
 
API Response Times: Fast and Consistent

Response time is a critical factor, especially when developers are iterating quickly. When testing with a cold start (after restarting the computer), Postman and Insomnia were slightly faster on a few small API calls. But Sparrow stayed close behind. It was never the slowest, and often came very close to the top tools—even though it's much lighter.
 
With a warm start (opening the app again without rebooting), Sparrow did even better. Thanks to cached system resources, its response times improved a lot and came very close to Postman and Insomnia.While it may not always lead in raw speed, it remains reliably fast, especially considering its minimal resource usage.
 
RAM Usage: The Clear Leader in Efficiency

When it comes to memory usage, Sparrow leads without question. On cold start, Sparrow used approximately 256 MB of RAM, and even less—just 236 MB—during warm start. This is dramatically lower than Postman, which consumed around 470 MB, and Apidog, which ballooned to over 850 MB. Even Bruno, which markets itself as lightweight, used more RAM than Sparrow. For developers running resource-heavy IDEs, databases, and local servers, Sparrow’s low memory footprint is a serious advantage.
 
Startup Time: Built for Speed

In terms of launch time, Sparrow consistently opened faster than the competition. On cold start, it launched in about 8 seconds, matching Bruno and beating Postman, Insomnia, and Apidog. In warm start conditions, it was even faster—taking only 5 seconds to become fully operational. This matters because developers often switch tools multiple times a day. Saving a few seconds per launch can add up to hours across a month.
 
Offline Capabilities: A Developer-Centric Design

Offline support is often ignored, but it’s very important—especially for developers working in remote areas, during travel, or in places with poor internet.

None of the tools we tested could send API requests completely offline. But Sparrow still stands out.

Even without an internet connection, Sparrow lets you:

• Create collections
• Build test flows
• Set up environments

Other tools like Postman and Insomnia only let you work with cached data. Apidog and Bruno allow some offline editing, but they don’t support full testing workflows.
 
Sparrow gives you more freedom to work offline, which is great for mobile developers, freelancers, or anyone working in secure or low-connectivity environments.
 
Developer Experience: Simple, Structured, Thoughtful

What truly differentiates Sparrow from its peers is the user experience. It’s designed to get out of your way. There’s no clutter, no unnecessary UI complexity, and no features that feel bolted on. Everything—from creating a collection to building a test flow—is structured, minimal, and fast.

Sparrow is built with developers in mind. It includes helpful features like:

• A markdown-friendly editor
• A testing interface that works offline

While many tools cater to complex enterprise setups with feature-heavy environments, Sparrow strikes a balance — offering a streamlined, efficient experience that doesn’t overwhelm. It’s built for enterprises that value speed, clarity, and focus, without compromising on power
 
Final Thoughts

The performance and UX data paint a clear picture. Tools like Postman and Insomnia are powerful but increasingly heavy. Apidog offers robust features but at the cost of extreme system resource usage. Bruno strikes a middle ground but still feels bloated over time.
 
Sparrow is different. It is built for speed, precision, and performance. Whether you're a solo developer or part of an enterprise team, it delivers the core capabilities you need—secure, scalable, and lightning-fast—without the bloat. It’s everything you expect from a modern API tool, optimized for how today’s teams actually work.
 
In a development world where efficiency is king, the case for a faster, lighter API tool like Sparrow has never been stronger.
 
Explore Sparrow
Try it yourself at sparrowapp.dev. Experience the difference in speed, focus, and simplicity.