Softwr

Testing · head to head

k6 vs Zephyr Scale

k6 logo

k6

Testing

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

From
Free
Rated
-
Full reviewWebsite
Zephyr Scale logo

Zephyr Scale

Testing

Native test management for Jira

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.; Zephyr Scale tightly bound to Jira; limited standalone functionality outside Jira ecosystem
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which k6 and Zephyr Scale actually diverge.

Attributes where k6 and Zephyr Scale differ
Attributek6Zephyr Scale
Starting priceFreeOn request
Pricing modelOpen source, no licence feequote
Free tierYesNo
PlatformsWindows, macOS, Linux, Docker, KubernetesWeb

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 Zephyr Scale

Nothing recorded that k6 does not also cover.

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

Zephyr Scale

  • Test case management within Jira workflowsnot k6
  • Manual and automated test execution trackingnot k6
  • Cross-project test asset reusenot k6
  • Requirements traceability from stories to testsnot k6
  • CI/CD pipeline and BDD framework integrationnot 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.

Zephyr Scale

  • Tightly bound to Jira; limited standalone functionality outside Jira ecosystem
  • No-code automation features limited in Standard tier, expanded only in Advanced
  • Data residency feature unavailable for Essential tier, limiting enterprise compliance
  • Transparent cost structure not provided on marketing page

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

Zephyr Scale

On request

No published plan breakdown. See the Zephyr Scale review.

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 Zephyr Scale if

Nothing in the data separates Zephyr Scale from k6 on the points above - pick on price and on how each one feels to use.

Zephyr Scale review

Questions people ask

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

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.

Zephyr Scale: How much does Zephyr Scale cost?

Zephyr Scale pricing is not published on the website. Three tiers are available: Essential, Standard, and Advanced, plus QMetry for Jira. Contact SmartBear or visit Atlassian Marketplace for pricing details.

Source
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.

Zephyr Scale: Is there a free trial available?

Yes, Zephyr offers free trials for Essential, Standard, and Advanced tiers, as well as for QMetry. Visit the product page to start a trial.

Source
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.

Zephyr Scale: Does Zephyr Scale work outside of Jira?

Zephyr Scale is tightly integrated with Jira for test management. For standalone test management outside Jira, SmartBear offers QMetry as an alternative.

Source
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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