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Testing · head to head

k6 vs REST Client VSCode

k6 logo

k6

Testing

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

From
Free
Rated
-
Full reviewWebsite
REST Client VSCode logo

REST Client VSCode

APIs

VSCode extension for making HTTP requests and testing REST APIs

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.; REST Client VSCode limited to Visual Studio Code; not available as a standalone application
  • They diverge on capability: k6 covers JavaScript test scripts, REST Client VSCode covers REST Client.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which k6 and REST Client VSCode actually diverge.

Attributes where k6 and REST Client VSCode differ
Attributek6REST Client VSCode
Pricing modelOpen source, no licence feeUnknown
PlatformsWindows, macOS, Linux, Docker, KubernetesWindows, macOS, Linux
CategoryTestingAPIs
FoundedUnknown2016

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

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 REST Client VSCode

  • REST Client
  • HTTP requests
  • Response viewing
  • VSCode
  • Environment variables
  • Custom headers
  • VSCode extension support

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

REST Client VSCode

  • API Developmentnot k6
  • API Gatewaynot k6
  • API Testingnot k6
  • API Documentationnot k6
  • Microservicesnot 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.

REST Client VSCode

  • Limited to Visual Studio Code; not available as a standalone application
  • No support for WebSocket, gRPC, or other advanced protocols
  • No cloud sync or team server features; requires Git-based workflow

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

REST Client VSCode

Free

No published plan breakdown. See the REST Client VSCode 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 REST Client VSCode if

  • You need rest client.
  • You want to start without paying.
  • You work on Windows, macOS, Linux.
  • You also want http requests.
REST Client VSCode review

Questions people ask

Is k6 or REST Client VSCode better?
Neither clearly leads. k6 starts at Free and REST Client VSCode at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, k6 or REST Client VSCode?
k6 starts at Free and REST Client VSCode at Free.
Does k6 or REST Client VSCode run on more platforms?
k6 runs on Windows, macOS, Linux, Docker, Kubernetes. REST Client VSCode runs on Windows, macOS, 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 REST Client VSCode is typically brought in for.
What can k6 do that REST Client VSCode cannot?
k6 covers JavaScript test scripts, Thresholds and checks, Protocol coverage, Browser module. REST Client VSCode covers REST Client, HTTP requests, Response viewing, VSCode.

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.

REST Client VSCode: How much does REST Client VSCode cost?

REST Client VSCode is completely free and open source. It is available on the Visual Studio Code Marketplace with no subscription or licensing fees.

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.

REST Client VSCode: What authentication methods does REST Client support?

REST Client supports Basic Auth, Digest Auth, SSL certificates, Azure AD, and AWS Signature v4 authentication for API requests.

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.

REST Client VSCode: Can I save and manage multiple requests?

Yes. REST Client supports multiple requests per file using ### delimiters, request history with auto-save, environment variables for different configurations, and code snippet generation for multiple programming languages.

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.

REST Client VSCode: How do teams collaborate with REST Client?

REST Client requests are stored as text files that can be version-controlled in Git repositories. Teams collaborate by sharing requests through Git, making the API specs part of the codebase.

Source
REST Client VSCode: What protocols does REST Client support?

REST Client primarily supports HTTP/HTTPS and GraphQL. It does not support WebSocket, gRPC, or other advanced protocols available in desktop clients like Insomnia.

Source
REST Client VSCode: Is there cloud sync for REST Client requests?

No. REST Client has no built-in cloud sync or team server features. All collaboration and sharing relies on Git repository management.

Source
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