Contexta Performance Recorder

Record browser sessions and generate JMeter JMX scripts with automatic correlation detection and assertions.

Contexta Performance Recorder is a Chrome extension built for performance testers. It records browser sessions and generates production-ready JMeter test scripts (JMX), HTTP archives (HAR), and raw session JSON — locally on your device, with no account required. WHAT IT DOES Click Start, walk through your user journey in the browser, click Stop. The recorder captures every request and the full response body via the Chrome DevTools Protocol, then runs local analysis: it detects dynamic correlations (CSRF tokens, session cookies, redirect targets, JSON values), classifies form fields, generates response assertions from page titles and headings, and produces a JMX script you can drop straight into JMeter or include into a larger test plan. KEY FEATURES - Full HTTP request and response body capture (not just headers) - Automatic correlation detection — CSRF tokens, session cookies, dynamic IDs, redirect chains, ASP.NET ViewState - Field classification — input, hidden, radio, select, CSRF — drives parameterisation in the generated script - Response assertion generation from page titles and headings - Page fingerprints — pages are identified by content, not URL, so configs survive URL changes across environments - Three recording modes: Auto (new transaction on each navigation), Transaction (manual boundaries), Full (single block, split later) - Multiple export formats: JMX Fragment (for orchestrator use), JMX Standalone (full TestPlan), HAR 1.2, raw JSON, CSV test data template - Recognises NHS.UK and GOV.UK design system pages out of the box - 100% local processing — no telemetry, no analytics, no account needed PRIVACY All recording happens locally in your browser. The extension does not transmit data automatically; it does not run analytics or telemetry. Recordings can be optionally imported into Contexta Performance Studio — a companion product, also operated by Contexta, at studio.contexta.uk — when you click Import on a Studio page. See the privacy policy for full details on what data is collected and how it is handled. PERMISSIONS The extension uses Chrome's debugger permission to capture full HTTP request and response bodies — this is the only Chrome permission that exposes response bodies to extensions and is required for the core function. Recording only happens while you have a session active and explicitly click Start. BUILT FOR PERFORMANCE TESTERS This is not a generic HTTP capture tool. Every feature — correlation detection, field classification, assertion generation, JMX output — exists because production performance testing needs it.