# Gatling Convert From Jmeter

> Guide for converting Apache JMeter tests to Gatling. Use this skill whenever the user mentions JMeter, .jmx files, JMeter test plans, or asks to convert or migrate a JMeter test to Gatling.

- Skill: `gatling/gatling-convert-from-jmeter` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add gatling/gatling-convert-from-jmeter`
- Raw SKILL.md: https://api.skillmd.com/api/skills/gatling/gatling-convert-from-jmeter/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- License: Apache-2.0
- Author: gatling (https://skillmd.com/u/gatling)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/gatling/gatling-convert-from-jmeter

---


# Convert a JMeter test plan to a Gatling simulation

## Instructions

### Step 1: Find input JMeter test plan

- Search for files with `.jmx` extension
- If several files found, ask user to specify one

### Step 2: Specify output

Either find an existing Gatling project or initialize a new Gatling project:

- Try to find an existing project with the /gatling:gatling-detect-existing-project skill
- If no existing project is found, offer to create a new one with the /gatling:gatling-bootstrap-project skill

### Step 3: Conversion

- Convert the JMeter test to a Gatling test written in the specified language.
- Write the output to the appropriate source directory of the Gatling project.

#### ThreadGroup

Each ThreadGroup converts to a scenario.

IF `serialize_threadgroups` true:
- Chain the scenarios with `andThen`
ELSE:
- Just list the scenarios in the `setUp` block

#### Resource files

Files referenced in elements such as:

- CSVDataSet
- HTTPFileArgs

should be copied to the resources directory in the Gatling project.

#### Redirects

| JMeter                     | Gatling                     |
|----------------------------|-----------------------------|
| `follow_redirects` = true  | default setting, do nothing |
| `follow_redirects` = false | `disableFollowRedirect`     |

#### CSVDataSet

`CSVDataSet` converts to a csv feeder.

IF there are several instances of `CSVDataSet` referencing the same file name:
- IF `shareMode.group`:
  - Create a new csv feeder for each scenario
  ELSE:
  - Create a single feeder and use it in each scenario

#### JMESPathExtractor

The `jmesPath` Gatling check extracts Strings, meaning that non String values get serialized back into JSON.
Using `findAll` with `jmesPath` is a mistake, but you can tell Gatling the expected type with an extra step.
Note that the check will then fail if the actual value doesn't match the expected type.

```
jmesPath("foo").ofString()
jmesPath("foo").ofBoolean()
jmesPath("foo").ofInt()
jmesPath("foo").ofLong()
jmesPath("foo").ofDouble()
// JSON array
jmesPath("foo").ofList()
// JSON object
jmesPath("foo").ofMap()
// anything
jmesPath("foo").ofObject()
```

##### matchNumber

`matchNumber` applies when the JMESPath expression returns an array and selects which element to use (1-based in JMeter).

IF `matchNumber` = 1:
- Use a JMESPath expression that selects the first element directly, e.g. `jmesPath("foo[0]")`

IF `matchNumber` = -1 (random):
- Extract the full array with `jmesPath("foo").ofList()`, then pick a random element in a subsequent `exec` block

IF `matchNumber` > 1:
- Use a JMESPath expression that indexes into the array, e.g. `jmesPath("foo[N-1]")` (0-based index)

#### Functions

Some functions have variants that save the result to a variable (e.g.: `__Random(0,10,myVar)`) but Gatling
Expression Language cannot save variables as a side effect.

IF a variable needs to be saved inside the function AND the function is used within an Expression Language
- Move the code to an exec block that allows saving variables

When parsing dates, use `java.time.format.DateTimeFormatter.ofPattern` with system default zone and store it
outside a function to avoid creation cost overhead.

For regular expression, use `java.util.regex.Pattern.compile` and store it outside a function to avoid creation cost
overhead.

Convert these functions to what JMeter uses under the hood:

- `changeCase`: `toUpperCase` or `toLowerCase` with `Locale.ROOT` or `capitalize`
- `digest`: `java.security.MessageDigest`
- `urldecode`: `java.net.URLDecoder.decode`
- `urlencode`: `java.net.URLEncoder.encode`
- `UUID`: `java.util.UUID.randomUUID`

Import `org.unbescape:unbescape` for the following escaping functions:

- `escapeHtml`: `HtmlEscape.escapeHtml5`
- `escapeXml`: `XmlEscape.escapeXml10`
- `unescape`: `JavaEscape.unescapeJava`
- `unescapeHtml`: `HtmlEscape.unescapeHtml`

### Step 4: Verify the code compiles

Use the build-tool skill if available.

### Step 5: Post conversion

After the conversion in Step 3, prompt the user for possible enhancements that are more idiomatic to Gatling.

IF `ThreadGroup.ramp_time` is 0 or 1:
- Suggest converting `rampUsers` to `atOnceUsers`