A leaner runtime
50–80% less memory and up to 50% less CPU than JMeter 5.6.3, through lazy decompression, response retention modes, lightweight cloning, and lazy diagnostics.
BreakTest, the modern, independent fork of Apache JMeter™.
BreakTest continues the JMeter workflow with JMX compatibility and a modernized engine. It adds HTTP/2 and HTTP/3, parallel requests, HAR import, recorded-versus-replayed diffs, and AI-assisted correlation. It also uses 50–80% less memory than JMeter 5.6.3. Keep the scripts and knowledge you already have, with more control, more realistic load, and a better debugging experience.
Forked from JMeter 5.6.3
45+ features added & improved
50–80% less memory
HTTP/2 · HTTP/3 beta
AI Repair included free
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The initial Community release is here.
Everything below is in the free download: a faster runtime, modern protocols, browser recording, portable compressed project files, and AI-assisted scripting, all in one desktop and command-line distribution.
Modern HTTP and native UDP
First-class HTTP/2 on Apache HttpClient 5, Brotli and Zstandard decoding, plus native UDP Request and Receiver samplers with configurable codecs and per-user sockets.
Browser recording built in
Install the official BreakTest HAR Recorder, name transactions while you click, then import the HAR into a complete test plan. Edge and Firefox recorders also ship with the tool.
Realistic workload modelling
Open and closed models in one Thread Group, with phases, even-arrival scheduling, and pacing. Parallel, Fork, and parallel ForEach controllers model browser-style concurrency.
Portable compressed project files
Compressed .jmx project files include the test plan and recorded request and response data, keeping everything together when the project moves.
AI-assisted repair
Claude Code, Codex, and MCP agents inspect and repair plans transactionally. Failed changes roll back through undo, and incomplete runs report as blocked.
Released under the BreakTest Community Source License 1.0 and free for testing systems operated by your own organization.
Why we forked JMeter
JMeter deserved better than maintenance mode.
We've spent our careers running load tests with JMeter. JMeter's foundation is genuinely good. That's why thousands of teams still build on JMX after twenty years.
But the project itself has slowed to a crawl. JMeter 5.6.3 shipped in January 2024, and little has happened since. Meanwhile the tool still drags along three HTTP stacks, BeanShell, Rhino JavaScript, and RMI-based remote testing. The problems performance engineers actually face every day, including correlation, debugging, and resource usage at scale, have barely changed since 2015.
So we forked 5.6.3 and did the work: one modern HTTP client with first-class HTTP/2, HTTP/3 in beta, 50–80% less memory and up to 50% less CPU, undo/redo, a results tree that shows the details you actually need, and AI-assisted script repair. The legacy paths that blocked progress are gone.
The goal is simple: make BreakTest the best performance testing tool available, and keep it free, with the best scripting experience of any tool, paid ones included. We fund the work with BreakTest Enterprise, the platform for running these tests at scale. That model keeps the tool itself free for testing your own organization's systems, under the BreakTest Community Source License.
What changed
A modern engine under a familiar workflow.
More than 45 features added or substantially improved since the fork. The short version:
Engine
- Modern HTTP/2 and HTTP/3HttpClient 5 handles HTTP/1.1 and HTTP/2 with protocol negotiation, Brotli, Zstandard, and working NTLM. Native HTTP/3 support is available in beta.
- A far leaner runtime50–80% less memory and up to 50% less CPU than JMeter 5.6.3, measured on the same plans.
- Realistic load shapesClosed and open workload models in one Thread Group; Parallel, Fork, and parallel ForEach controllers.
- Runs you can steerPause and resume a live test; stops that actually stop.
- UDP supportNative UDP Request and Receiver samplers with text, hex, and raw payloads.
Scripting
- Recording built inHAR import wizard, recorded-vs-replayed diffs, recordings that travel inside the JMX.
- Fail when correlation failsExtractors can fail the sampler when nothing matches, so broken correlation is caught immediately without separate assertions.
- AI Repair, included freeClaude Code or Codex fixes extractors, headers, and Groovy over MCP, either as a full repair or one targeted change.
- More control, fewer clicksSee more of your plan at a glance, navigate less, and build and correlate scripts much faster than before.
The scripting experience
From recording to working script, without the grind.
Most of a performance tester's time goes into scripting and correlation, not running tests. That's the part we set out to fix first.
- Install the official BreakTest HAR Recorder from the Chrome Web Store, name transactions while you click, then use File → Import HAR to build the plan with your steps and real think times
- Compare recorded vs. replayed responses side by side while you debug
- Let extractors fail the sampler the moment correlation breaks
- Hand the broken plan to AI Repair, which fixes selectors, extractors, and Groovy from your instructions
- Restructure large plans confidently with real undo/redo
When one machine isn't enough
BreakTest Enterprise: the same scripts, at scale.
The free tool covers scripting and local runs. Enterprise is the platform around it: it runs those same tests at scale, manages them as a team, and turns the results into decisions.
- Millions of virtual users on generators you control, across Docker, Kubernetes, cloud, or on-premises environments
- Live results during the run: streaming charts, metrics retained for every measurement, and full request/response evidence for errors
- Test management for teams: projects, scenarios, history that stays comparable
- CI/CD integration with SLO gates: one API call runs the test, and the result gates the release
- Analysis after the run: run-to-run comparison, AI findings, PDF/HTML reports
- Synthetic monitoring: reuse test scripts as production monitors between load tests
- Runs BreakTest, JMeter, and k6, deployed on-premises or as SaaS
Get started
Download BreakTest, free.
One archive with the GUI, the CLI runtime, and AI Repair. Open an existing JMX and see the difference in the first ten minutes. Requires Java 21+. After that, the GUI keeps itself up to date.
Break it before your users do.
Start free on your machine. When you need scale, test management, and live results, Enterprise is ready.