perf-migrator
perf-migrator is the free converter at tools.martkos-it.co.uk. It takes a Chrome HAR recording or an existing JMeter, k6 or Gatling script and gives you back a runnable script in whichever of the three you need — all six directions, plus HAR to any of them.
Free, up to 25 HTTP requests — enough for a single user journey. There is nothing to install and no account.
It runs in your tab
Section titled “It runs in your tab”The conversion engine is compiled to WebAssembly and loaded into the page. Your file is read by JavaScript, converted in memory and handed back as a download. It is never uploaded, and the page’s Content-Security-Policy allows connections to nothing but the origin that served it — so that claim is enforced by the browser rather than promised in copy. Open DevTools → Network and watch: converting issues no requests at all.
That matters most for a HAR, which routinely carries production hostnames, cookies, auth tokens and response bodies.
What it does not do
Section titled “What it does not do”It does not correlate. The output replays the values the recording captured — session ids, CSRF tokens, anything the server issued at the time — and those are stale on the next run. A script full of them still runs, which is exactly why the page says so on every result.
Extracting them is what perf-script-studio does, along with unlimited size, batch conversion and merging extractors into a JMX you already have. The correlation pattern library is deliberately not in the browser build: a public WebAssembly module can be disassembled.
The paid CLI
Section titled “The paid CLI”perf-migrator’s command-line tool was merged into
perf-script-studio — one binary, one £99 price, every
direction. The perf-migrator command name still ships as a shim beside it, and
PERF_MIGRATOR_LICENSE is still honoured, so existing pipelines keep working. The £79
single-direction and £149 bidirectional tiers are withdrawn, and a single-direction key is
no longer restricted to one direction.