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Testing · head to head

k6 vs Sauce Labs

k6 logo

k6

Testing

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

From
Free
Rated
-
Full reviewWebsite
Sauce Labs logo

Sauce Labs

Testing

Cloud device and browser testing platform, priced per plan tier with unlimited testing minutes rather than metered by the minute

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only k6 has a free tier, so it costs nothing to try first.
  • 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.; Sauce Labs every published tier includes only a single parallel test session by default, so any team wanting to run multiple tests simultaneously needs to negotiate additional parallel sessions, which is not transparently priced on the public page.
  • They diverge on capability: k6 covers JavaScript test scripts, Sauce Labs covers Real device cloud.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which k6 and Sauce Labs actually diverge.

Attributes where k6 and Sauce Labs differ
Attributek6Sauce Labs
Starting priceFreeOn request
Pricing modelOpen source, no licence feePer month by parallel session count and device category
Free tierYesNo
PlatformsWindows, macOS, Linux, Docker, KubernetesWeb, iOS, Android

Identical on both: 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 Sauce Labs

  • Real device cloud
  • Virtual device cloud
  • Live manual testing
  • Video and log capture
  • Sauce AI agents
  • Unlimited testing minutes and users

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 Sauce Labs
  • Generating tens of thousands of requests per second from a small number of machines without a load generator fleetnot Sauce Labs
  • Testing gRPC and WebSocket services with the same tooling and thresholds used for HTTP endpointsnot Sauce Labs
  • Correlating a load test against existing dashboards for an organisation already running Grafana and Prometheusnot Sauce Labs

Sauce Labs

  • A QA team running Selenium or Appium test suites that needs cloud device and browser coverage without maintaining a physical labnot k6
  • A team wanting manual live testing sessions on real devices for exploratory or accessibility testingnot k6
  • An organisation needing video, screenshot and log capture on every automated test run for debugging flaky failuresnot k6
  • An enterprise wanting AI-assisted test authoring and insights alongside device cloud executionnot 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.

Sauce Labs

  • Every published tier includes only a single parallel test session by default, so any team wanting to run multiple tests simultaneously needs to negotiate additional parallel sessions, which is not transparently priced on the public page.
  • Enterprise pricing, where AI agents and SSO live, is quote-only, so the most capability-rich tier loses the pricing transparency of the lower tiers.
  • It competes directly with BrowserStack on almost identical device cloud fundamentals, and the two vendors leapfrog each other on device inventory and pricing often enough that a comparison made today can be outdated within a year.
  • Real device availability for less common device and OS combinations can queue during peak usage, which affects CI pipelines that expect on-demand execution.
  • The unlimited-minutes model rewards teams that run tests constantly and penalises smaller teams paying the same base price for occasional, low-volume use.

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

Sauce Labs

On request
  • Live Testing$39/month
    • Annual billing, 49 US dollars a month billed monthly
    • 1 parallel test, unlimited users and testing minutes
    • Manual cross-browser and mobile app testing
  • Virtual Device Cloud$149/month
    • Annual billing, 199 US dollars a month billed monthly
    • 1 parallel test, unlimited users and testing minutes
    • Automated and manual testing on emulators and simulators
  • Real Device Cloud$199/month
    • Annual billing, 249 US dollars a month billed monthly
    • 1 parallel test, unlimited users and testing minutes
    • Access to real mobile devices
  • Enterprise$undefined/year
    • Custom parallel session count and pricing
    • Sauce AI Test Authoring and Insights agents
    • SSO, private device cloud, professional services

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 Sauce Labs if

  • You need real device cloud.
  • You work on Web, iOS, Android.
  • You also want virtual device cloud.
Sauce Labs review

Questions people ask

Is k6 or Sauce Labs better?
Neither clearly leads. k6 starts at Free and Sauce Labs at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, k6 or Sauce Labs?
k6 has a free tier; the other does not. Paid plans start at Free for k6 and On request for Sauce Labs.
Does k6 or Sauce Labs run on more platforms?
k6 runs on Windows, macOS, Linux, Docker, Kubernetes. Sauce Labs runs on Web, iOS, Android.
Can I use k6 for free?
Yes. k6 has a free tier, so you can try it without paying. Sauce Labs starts at On request.
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 Sauce Labs is typically brought in for.
What can k6 do that Sauce Labs cannot?
k6 covers JavaScript test scripts, Thresholds and checks, Protocol coverage, Browser module. Sauce Labs covers Real device cloud, Virtual device cloud, Live manual testing, Video and log capture.

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.

Sauce Labs: Is Sauce Labs priced by testing minutes?

No, every published plan includes unlimited testing minutes and unlimited users; the pricing lever is the number of parallel test sessions and device category.

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.

Sauce Labs: How does it differ from BrowserStack?

Both offer equivalent real and virtual device cloud testing for Selenium and Appium; differences are mainly in device inventory specifics, parallel session pricing and AI feature rollout, which change often enough to need a current comparison.

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.

Sauce Labs: Do I need Appium or Selenium separately?

Yes, Sauce Labs provides the device and browser infrastructure; test scripts are still written against the open source Selenium or Appium frameworks.

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.

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