Softwr

Testing · head to head

k6 vs Testsigma

k6 logo

k6

Testing

Load testing tool with JavaScript tests on a Go runtime, now owned by Grafana Labs

From
Free
Rated
-
Full reviewWebsite
Testsigma logo

Testsigma

Testing

Natural language test automation for web, mobile and API with a self hosted open source edition

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: k6 tests run on a JavaScript engine embedded in Go rather than on Node.js, so npm packages, Node built-ins and existing shared test utilities generally do not work without being bundled to plain JavaScript, and often not even then.; Testsigma the natural language layer is a fixed vocabulary rather than real English, so testers spend the first weeks learning which phrasings the parser accepts, which is learning a language after all.
  • They diverge on capability: k6 covers JavaScript test scripts, Testsigma covers Natural language authoring.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which k6 and Testsigma actually diverge.

Attributes where k6 and Testsigma differ
Attributek6Testsigma
Pricing modelOpen source, no licence feePer user per month
PlatformsWindows, macOS, Linux, Docker, KubernetesWeb, iOS, Android, Linux

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Testing).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in k6

  • JavaScript test scripts
  • Thresholds and checks
  • Protocol coverage
  • Browser module
  • Executors
  • xk6 extensions
  • Metrics output
  • Kubernetes operator

Only in Testsigma

  • Natural language authoring
  • Unified web, mobile and API tests
  • Self hosted community edition
  • Cloud device and browser grid
  • Data driven runs
  • Custom functions

What people use each for

The jobs each tool is most often brought in to do.

k6

  • Gating a deployment pipeline on a threshold such as 95th percentile latency under a defined arrival ratenot Testsigma
  • Generating tens of thousands of requests per second from a small number of machines without a load generator fleetnot Testsigma
  • Testing gRPC and WebSocket services with the same tooling and thresholds used for HTTP endpointsnot Testsigma
  • Correlating a load test against existing dashboards for an organisation already running Grafana and Prometheusnot Testsigma

Testsigma

  • A team maintaining separate Selenium and Appium suites that wants one place for web and native mobile coveragenot k6
  • Organisations that must keep test data and execution on premises for regulatory reasonsnot k6
  • QA groups with manual testers being asked to automate without first learning Javanot k6
  • Evaluating low code test automation properly before committing budget, by running the free edition against the real applicationnot k6

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

k6

  • Tests run on a JavaScript engine embedded in Go rather than on Node.js, so npm packages, Node built-ins and existing shared test utilities generally do not work without being bundled to plain JavaScript, and often not even then.
  • The open source binary runs on a single machine, so distributed load requires the Kubernetes operator or the cloud service, and the operator is infrastructure your team has to run and debug.
  • The AGPL-3.0 licence on the core requires legal review at any company that intends to embed k6 in a product it distributes or offers as a service, which is a slower path than a permissively licensed tool.
  • There is no result storage in the open source tool, so trend history means standing up Prometheus, InfluxDB or Grafana Cloud before load testing produces anything comparable over time.
  • Since the Grafana Labs acquisition the roadmap serves the Grafana observability stack, so a buyer choosing k6 as a standalone tool should expect the standalone experience to receive less investment than the cloud and dashboard integration.
  • Grafana Cloud billing is by virtual user hour, so a long soak test at modest concurrency costs far more than its peak load suggests, and cost planning has to be done in virtual user hours rather than in test runs.

Testsigma

  • The natural language layer is a fixed vocabulary rather than real English, so testers spend the first weeks learning which phrasings the parser accepts, which is learning a language after all.
  • Anything conditional or arithmetic falls through to custom Java or JavaScript, and that code lives in the platform editor rather than your repository, where it gets no code review and no version history you control.
  • The community edition lags the cloud product and is not the version the vendor demonstrates, so a self hosted evaluation can understate or overstate what you would actually buy.
  • Cloud execution is billed separately from authoring seats, so a suite that grows from two hundred to two thousand tests changes the bill without anyone changing the plan.
  • Support and engineering are concentrated in Indian time zones, which slows incident turnaround for teams working in the Americas.

Pricing, plan by plan

k6

Free
  • k6 OSSFree
    • AGPL-3.0 licence
    • Full test engine, no virtual user limits
    • Runs on one machine unless distributed yourself
  • Grafana Cloud free tierFree
    • Includes a monthly allowance of virtual user hours
    • Hosted test results and dashboards
    • Shared with the rest of the Grafana Cloud free tier
  • Grafana Cloud k6$undefined/month
    • Billed by virtual user hours consumed
    • Load generation from multiple regions
    • Retained test history and comparison

Testsigma

Free
  • Community Edition$undefined/month
    • Self hosted, open source, no licence fee
    • You supply the infrastructure and the browser or device grid
  • Cloud$undefined/month
    • Priced per authoring user with additional charges for parallel cloud executions and device minutes
    • Published tiers exist but the figures that matter at team scale come from sales

Which should you pick?

Choose k6 if

  • You need javascript test scripts.
  • You want to start without paying.
  • You work on Windows, macOS, Linux, Docker, Kubernetes.
  • You also want thresholds and checks.
k6 review

Choose Testsigma if

  • You need natural language authoring.
  • You want to start without paying.
  • You work on Web, iOS, Android, Linux.
  • You also want unified web, mobile and api tests.
Testsigma review

Questions people ask

Is k6 or Testsigma better?
Neither clearly leads. k6 starts at Free and Testsigma at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, k6 or Testsigma?
k6 starts at Free and Testsigma at Free.
Does k6 or Testsigma run on more platforms?
k6 runs on Windows, macOS, Linux, Docker, Kubernetes. Testsigma runs on Web, iOS, Android, Linux.
Can I use k6 for free?
Both have a free tier, so you can try either at no cost before committing.
What is k6 best used for?
k6 is most often used for gating a deployment pipeline on a threshold such as 95th percentile latency under a defined arrival rate, generating tens of thousands of requests per second from a small number of machines without a load generator fleet, testing grpc and websocket services with the same tooling and thresholds used for http endpoints, correlating a load test against existing dashboards for an organisation already running grafana and prometheus. Of those, gating a deployment pipeline on a threshold such as 95th percentile latency under a defined arrival rate and generating tens of thousands of requests per second from a small number of machines without a load generator fleet are not what Testsigma is typically brought in for.
What can k6 do that Testsigma cannot?
k6 covers JavaScript test scripts, Thresholds and checks, Protocol coverage, Browser module. Testsigma covers Natural language authoring, Unified web, mobile and API tests, Self hosted community edition, Cloud device and browser grid.

Answered from the vendors’ own pages

k6: Can I use npm packages in a k6 test?

Usually not. Scripts run on a Go-embedded JavaScript engine with no Node.js runtime, so packages depending on Node built-ins fail and pure JavaScript libraries must be bundled first.

Testsigma: Is the open source edition genuinely usable in production?

Yes for self hosted execution, though it trails the cloud version on newer features and you maintain the grid yourself.

k6: Is k6 free?

The core tool is free under AGPL-3.0 with no virtual user limits. Grafana Cloud k6 is a paid service billed by virtual user hours, with a free monthly allowance.

Testsigma: Do testers need to know Selenium?

Not to write ordinary steps. They will need someone who does as soon as the suite needs custom functions or awkward waits.

k6: Does the Grafana acquisition affect the open source tool?

The tool remains open source and maintained, but investment is directed at making it a data source for Grafana, so standalone use is supported rather than prioritised.

Testsigma: Can it test native iOS and Android applications?

Yes, through Appium underneath, on the hosted device grid or your own devices.

k6: Can k6 replace a browser testing tool?

No. The browser module measures page-level metrics under load, but functional browser testing belongs in Playwright or a similar tool.

Share

Related pages

More on k6

More on Testsigma

Keep looking

Other head to heads