An open-source project dedicated to measuring internet responsiveness.
Most internet speed tests measure throughput: how many megabits per second your connection can deliver. Bufferbloat.org measures something different: how responsive your connection remains while it is under load.
Website: https://bufferbloat.org
I built Bufferbloat.org because I couldn't find the tool I wanted.
Most people are told to judge their internet connection by download speed. More technical users know to look at ping. Both are useful, but neither fully explains a question millions of people ask every day:
"Why is my internet still laggy if I have 500 Mbps?"
A connection can deliver hundreds of megabits per second while video calls freeze, games stutter, websites hesitate and remote desktops become frustrating to use. The problem is often not bandwidth, but latency under load.
Networking researchers have understood this for years. Yet, despite excellent research and commercial products, I was surprised by how few open, transparent and browser-based tools existed to measure it.
I wanted a tool whose methodology anyone could inspect, whose implementation anyone could verify, and whose measurements anyone could improve.
So I built one.
Bufferbloat is excessive latency caused by oversized or overloaded network queues.
When a connection becomes busy, packets can spend too long waiting before being transmitted. Throughput may remain high while responsiveness deteriorates dramatically.
That's why a connection can achieve an excellent speed test result and still perform poorly during video calls, online gaming, browsing or other interactive applications.
This project focuses on measuring internet responsiveness, not just throughput.
Internet measurement should be transparent.
Measurements should be reproducible. Methodology should be public. Implementation should never be a black box.
Bufferbloat.org is built around those principles.
The project provides:
- Open measurement methodology
- Inspectable source code
- Browser-based testing
- Privacy-first design
- Reproducible measurements
- Community-driven development
The browser test starts with a short warm-up, then records three scored measurement phases:
- Quiet-line latency
- Download latency under load
- Upload latency under load
Results include:
- Median idle latency
- Median download latency under load
- Median upload latency under load
- Download throughput
- Upload throughput
- Overall responsiveness grade
- Plain-language diagnosis
- Structured technical details
- CSV export of the measurement record
The result grade is primarily about latency stability under load. Throughput is reported because it matters for real applications, but low bandwidth by itself is not treated as bufferbloat.
Throughput tells you how much data your connection can move.
Responsiveness tells you how quickly your connection continues to react while moving that data.
For many everyday applications, responsiveness has a greater impact on user experience than peak bandwidth.
Examples include:
- Video conferencing
- Online gaming
- Web browsing
- Remote desktop
- Voice calls
- Cloud development
- Streaming while other devices are active
- Browser-based latency-under-load measurement
- Open-source measurement engine
- Download and upload stress testing
- Median latency reporting
- Real-time visualisation
- Mobile-friendly interface
- Light and dark mode
- Public measurement methodology
Install dependencies:
npm installRun the development server:
npm run devOpen:
http://localhost:3000
Build for production:
npm run build- Next.js App Router
- TypeScript
- Cloudflare
- Vercel
Contributions are welcome.
Areas of particular interest include:
- Measurement methodology
- Browser compatibility
- Accessibility
- Documentation
- Privacy-preserving diagnostics
- Visualisation and reporting
If you disagree with the methodology, find a bug, or have an idea for improving the measurements, please open an issue or submit a pull request.
The core measurement is orchestrated by the browser. Test traffic is generated from the page against public measurement endpoints, and no local helper application is required.
Optional email signup data is stored separately and should never be committed:
data/signups.json
Bufferbloat.org is an independent project created and maintained by Emanuele Brandi.
I've spent more than two decades trying to make the web work a little better. Somewhere along the way, I developed an obsession with things that are measurable, transparent and useful, and lost almost all patience for black boxes.
Bufferbloat.org is an independent open-source project. I built it because I believe the web needs transparent and community-owned tools more than ever, and because the tools we use to measure the web should themselves be open to inspection, scrutiny and improvement.
I hope you find it useful. If you do, whether as an individual or an organisation, please consider contributing.
- Website: https://bufferbloat.org
- GitHub: https://github.com/pelagus
- LinkedIn: https://linkedin.com/in/ebrandi
MIT