JSR223 Groovy Playground & Code Builder

NameParametersSpace-separated; available as Parameters string and args array.

Groovy Codeimport groovy.json.JsonSlurper String responseText = prev.getResponseDataAsString() if (!responseText || responseText.trim().isEmpty()) { log.warn("Response body is empty, cannot parse JSON.") return } def json = new JsonSlurper().parseText(responseText) // Find active items with status == 'ACTIVE' def activeItems = json.items?.findAll { it.status == 'ACTIVE' } if (activeItems && !activeItems.isEmpty()) { def picked = activeItems[java.util.concurrent.ThreadLocalRandom.current().nextInt(activeItems.size())] vars.put("selected_item_id", picked.id.toString()) vars.put("selected_item_name", picked.name.toString()) } else { log.warn("No active items found in JSON response.") vars.put("selected_item_id", "NOT_FOUND") }Groovy is not executed in the browser — this tool lints for JMeter-specific pitfalls and generates the JMX element for you to run in JMeter.

Bindings Used-

Errors-

Warnings-

Lines-

Static Analysis

Bindings for Selected Element

Groovy Script (.groovy)

JMX Element Snippet

Paste into a .jmx under the target sampler's <hashTree>, or import via JMeter GUI → Edit → Paste.

Copy GroovyDownload .groovyCopy JMX SnippetDownload .xml snippetReset

Use Groovy tools through MCP

Call get_jsr223_recipe for curated examples, or lint_groovy_script to review your own code and generate JSR223 element XML.

claude mcp add jmeter-docs https://docs.jmeter.ai/api/mcp --transport http

This builder does not execute Groovy. Review generated code and run it in a controlled JMeter test before load testing. See JSR223 Sampler Reference and JMeter MCP Reference.

Why Groovy over BeanShell

JMeter supports Groovy through JSR223 compilation caching, while BeanShell is interpreted and substantially slower in a hot sampling path. Groovy also provides modern Java interoperability, mature JSON support, and access to JMeter’s documented script bindings.

This page is a builder and static analyzer. Groovy cannot execute in the browser. The tool inspects source text for JMeter-specific pitfalls and generates files for you to review and run in JMeter; it does not validate runtime types, external classes, network access, or script behavior.

Binding availability

Every JSR223 element exposes the common bindings log, Label, FileName, Parameters, args, ctx, vars, props, and OUT. Element-specific bindings differ:

Element	Available bindings
JSR223 Sampler	log, Label, FileName, Parameters, args, ctx, vars, props, OUT, SampleResult, sampler
JSR223 PreProcessor	log, Label, FileName, Parameters, args, ctx, vars, props, OUT, sampler
JSR223 PostProcessor	log, Label, FileName, Parameters, args, ctx, vars, props, OUT, sampler, prev
JSR223 Assertion	log, Label, FileName, Parameters, args, ctx, vars, props, OUT, SampleResult, AssertionResult, prev, sampler
JSR223 Timer	log, Label, FileName, Parameters, args, ctx, vars, props, OUT, sampler
JSR223 Listener	log, Label, FileName, Parameters, args, ctx, vars, props, OUT, sampleResult, prev, sampleEvent, sampler

Binding names are case-sensitive. For example, SampleResult is available in a Sampler or Assertion, while lowercase sampleResult and sampleEvent belong to a Listener. prev is available to PostProcessors, Assertions, and Listeners, but not PreProcessors or Timers; sampler is available to all six element types, including Listeners.

Anti-patterns this linter catches

Rule ID	Severity	What it catches
EMPTY_SCRIPT	Error	Blank code
THREAD_SLEEP	Error	Thread.sleep(...) or sleep(...) blocking a JMeter worker thread
JMETER_VAR_INTERPOLATION	Warning	${name} expansion without a preceding Groovy local declaration
SYSTEM_OUT	Warning	System.out, System.err, or statement-level println(...)
NEW_RANDOM_PER_CALL	Info	A new Random instance created on each invocation
REGEX_COMPILE_IN_SCRIPT	Info	Pattern.compile(...) in the hot script path
UNAVAILABLE_BINDING	Error	A known binding used by the wrong JSR223 element type
BEANSHELL_IMPORT	Error	BeanShell imports or API references inside Groovy
LEGACY_JSONSLURPER_CLASSIC	Info	JsonSlurperClassic instead of JsonSlurper
PROPS_MUTATION_IN_LOOP_HOT_PATH	Info	Writes to shared JMeter properties with props.put(...)
SCRIPT_TOO_LONG	Warning	Inline code over 200,000 characters that belongs in a .groovy file

For dynamic JMeter values, prefer vars.get("name") or props.get("name"). Substitution such as ${token} happens before Groovy compilation, can create a new compiled script for each value, and can break syntax when data contains quotes or other special characters.

How to use the generated JMX snippet

1. Select the JSR223 element that matches where the script should run.
2. Fix error-level binding or scripting findings.
3. Copy the generated element and its following <hashTree/>.
4. Paste it under the target element’s <hashTree> in the .jmx, or use JMeter GUI → Edit → Paste.
5. Open the plan in JMeter, confirm the tree location, and run a one-user smoke test with assertions before applying load.

The generated element uses TestBeanGUI, Groovy, and a non-empty cacheKey so JMeter can cache compiled scripts. Downloading the .groovy variant is useful when scripts are shared across plans or maintained in source control; set that file through the JSR223 FileName field in JMeter.

Use via MCP

Connect an MCP-compatible agent:

claude mcp add jmeter-docs https://docs.jmeter.ai/api/mcp --transport http

Ask the agent to call get_jsr223_recipe by recipe name or category to retrieve the curated JWT, HMAC, dynamic header, JSON extraction, and custom logging examples used by this builder. For your own script, call lint_groovy_script with the code and JSR223 element type to receive the same findings, binding analysis, and optional ready-to-paste JMX element XML.