A practical guide for teams moving an existing Postman collection to a Karate test suite. What converts automatically, what you'll have to rewrite, and how to do the transition without freezing the team.
Last updated: May 2026
A typical Postman-to-Karate migration takes 1–3 weeks of part-time work for a collection of 100–300 requests. The importer handles the boring part — URLs, headers, request bodies, folder structure. You'll spend most of your time rewriting pm.test JavaScript as Karate match assertions and converting pre-request scripts to Background steps. Run both tools side-by-side until the Karate suite is trusted, then retire Postman.
Honest estimates for a mid-size collection (100–300 requests, 5–15 folders, basic auth + a few pre-request scripts).
.feature file layoutpm.test JS assertions → matchBackground or helper features{{$randomEmail}}, etc.)pm.environment.setmvn test / JUnit runnerTranslate what you already know in Postman to its Karate equivalent. Keep this table open while you migrate.
| Postman | Karate | Notes |
|---|---|---|
| Collection | A folder of .feature files |
One feature per logical surface (Users, Orders, Auth) |
| Folder | Subdirectory of features | Karate JUnit runner picks them up by package |
| Request | Scenario |
The request name becomes the scenario name |
| Pre-request script | Background steps or * def |
For shared setup, extract to a helper feature called via call read() |
Tests tab (pm.test) |
Then status / match |
Declarative deep-equals replaces field-by-field JS assertions |
| Environment | karate-config.js |
Branch on karate.env (dev, staging, prod) |
{{baseUrl}} |
#(baseUrl) or variable interpolation |
Defined once in karate-config.js |
pm.environment.set('x', val) |
* def x = val |
Use karate.set() to share across features |
{{$randomEmail}} |
* def email = 'u_' + java.util.UUID.randomUUID() + '@test.com' |
Inline Java/JS gives you anything Postman's dynamic vars do |
| OAuth2 token helper | call read('classpath:auth.feature') |
One feature returns the token, every test calls it |
| Collection runner / Newman | JUnit runner (mvn test) |
No extra CLI install — same binary local and in CI |
| Iterations + data file | Scenario Outline + Examples |
Or read('data.json') with a call loop |
| Mock server | Karate Mock | Local, stateful, uses the same DSL as your tests |
A "create a user, then fetch it" flow — the kind of two-step request chain that lives in nearly every Postman collection.
// Request 1: Create User
// Pre-request Script
const email = `user_${Date.now()}@test.com`;
pm.environment.set('email', email);
// Body (raw JSON)
{
"name": "John",
"email": "{{email}}"
}
// Tests
pm.test("Status 201", () => {
pm.response.to.have.status(201);
});
pm.test("Has id", () => {
const j = pm.response.json();
pm.expect(j.id).to.not.be.null;
pm.environment.set('userId', j.id);
});
// Request 2: Get User
// URL: {{baseUrl}}/users/{{userId}}
pm.test("Status 200", () => {
pm.response.to.have.status(200);
});
pm.test("Email matches", () => {
const j = pm.response.json();
pm.expect(j.email).to.eql(
pm.environment.get('email')
);
});users.feature)
~14 lines
Feature: Create then fetch a user
Background:
* url baseUrl
* def email = 'user_' + java.lang.System.currentTimeMillis() + '@test.com'
Scenario: Create and read back
Given path '/users'
And request { name: 'John', email: '#(email)' }
When method post
Then status 201
And match response == { id: '#notnull', name: 'John', email: '#(email)' }
* def userId = response.id
Given path '/users', userId
When method get
Then status 200
And match response.email == emailSame flow, half the lines, no JavaScript — and the whole file lives in your Git repo with a normal diff.
Roughly in order. Phases 1–3 take a couple of days; phase 4 is the bulk of the work; phases 5–6 are short.
Export your collection(s) and environments as JSON. Count requests, folders, environments, and pre-request scripts. Tag each script as trivial (set a header, generate a value) or complex (multi-step logic, conditional branching). The complex ones drive your timeline.
Create a Maven or Gradle project, add karate-junit5 as a dependency, and set up karate-config.js with one block per environment. Install the IntelliJ or VS Code plugin so you get syntax highlighting and run-from-the-IDE. IntelliJ plugin · VS Code plugin.
Karate ships an importer that converts a Postman collection JSON into a starter set of .feature files. It handles request shape (URL, method, headers, query, body) and folder structure. Don't expect it to convert your pm.test JS — that's deliberate, and rewriting them is faster than untangling auto-generated code.
This is where the time goes. Three big buckets:
pm.test() block becomes one or two lines using match. Most field-by-field assertions collapse into a single match response == {...}.Background lines. Anything reused (login, build a signed header) goes in a helper feature called via call read('classpath:auth.feature').karate-config.js so every test gets it for free.Karate runs as a JUnit test — the same step you use for any other test in your pipeline. No Newman install, no per-month run cap, no SaaS dependency. Add parallel execution by setting the threads argument; Karate's runner handles the rest. JUnit XML and Cucumber HTML reports come out of the box.
Don't cut over in one drop. Keep Newman running on the existing pipeline while the Karate suite runs alongside it. Compare results for a sprint or two, fix discrepancies, then delete the Postman job. Most teams retire Postman as their CI tool but keep individual seats for ad-hoc API exploration.
Specific places teams get stuck. Click any to expand.
In Postman this is usually a folder-level pre-request script that hits the auth endpoint and stuffs the token into an environment variable. In Karate, write one auth.feature that does the login and returns the token. Call it once from karate-config.js and every test inherits the Authorization header automatically.
{{$randomEmail}}, {{$timestamp}})
Karate doesn't ship a fixed list, but it gives you Java and JavaScript inline so you can produce anything. java.util.UUID.randomUUID(), java.lang.System.currentTimeMillis(), or any helper from a util feature. If you use the same generator across the suite, define it once in karate-config.js and reference it as a global.
pm.environment.set
Postman teams use pm.environment.set to thread state from one request to the next. In Karate this is just sequential steps in a single Scenario. response is automatically available after every call — * def userId = response.id and you're done. No special API needed.
Two options. For a small fixed set, use Scenario Outline with Examples — same idea as a Postman runner CSV but inline. For larger or external datasets, read('data.json') and loop with call. Both run in parallel without extra config.
Karate has a multipart file keyword that takes a path and a MIME type. Same flexibility as Postman's form-data tab, but as a one-line declaration in your feature file. No external script needed for binary payloads.
GraphQL is just a POST with a JSON body containing query and variables. Karate has no special-case GraphQL syntax, but it doesn't need one — the request shape is identical to any other JSON POST. Read schemas with read('query.graphql') if you want to keep them in separate files.
There's no direct equivalent — but most teams replace cloud monitors with a CI cron job. GitHub Actions, GitLab schedules, or Jenkins triggers can run your Karate suite on the same cadence as a Postman monitor, against any environment, with no per-run pricing. The same suite that runs in CI runs as your monitor.
The single most common mistake we see is teams trying to flip the switch in one PR. It almost always stalls.
Instead: pick one folder — ideally a low-risk one with stable endpoints — and migrate it end-to-end while leaving everything else in Postman. Ship that to CI. Keep the Newman job running. Migrate the next folder. After a sprint or two, the Karate suite covers most of what matters and the Newman job has gone two weeks without finding anything new. That's when you delete it.
This way the team is never blocked, and you build confidence in the new suite before betting on it.
For a typical collection of 100–300 requests, plan on one to three weeks of part-time work. The importer handles request shape automatically; the bulk of the time goes into rewriting JavaScript assertions, pre-request scripts, and auth flows. Larger collections with heavy scripting (1000+ requests, complex chained logic) can take 4–6 weeks.
No. Most teams run Postman/Newman and Karate side-by-side for one or two sprints. Migrate one folder at a time, leave the rest in Newman, and cut over per surface as you build confidence. We strongly recommend this approach over a big-bang switch.
The importer converts request URL, method, headers, query parameters, and static request bodies into Karate Given/When/Then steps, and preserves your folder structure. It does not convert pm.test JavaScript assertions, pre-request scripts, dynamic variables, or chained-request logic — those need a manual rewrite. In practice that rewrite is faster than it sounds because the Karate equivalents are usually 1–3 lines each.
Yes, and many teams do. Postman (or Karate Xplorer) is great for ad-hoc exploration during development; Karate runs the automated regression suite in CI. The two are complementary, not competitive, at different points in the workflow.
Not for the day-to-day work. Karate's DSL is plain text — Given url, When method post, Then status 200. Most QA engineers are productive in hours, not days. The Java/JS escape hatch is there when you need to generate complex test data, but it's not on the critical path for writing or maintaining tests.
Reach out. We've helped dozens of teams through this migration and have seen most of the awkward edge cases. Get in touch — even if you're using only the open-source framework, we're happy to point you in the right direction.
Read the docs, join the community, or get a hands-on walkthrough from our team.