Flagger
Flagger: A focused Kubernetes operator for metric-driven canary delivery and rollback. Ranked #14 of 31 in Continuous Delivery Software by our editors (7.7/10); pricing: Open source; best for metric-driven Kubernetes canary delivery.
At a glance
- Editor score7.7 / 10
- PricingOpen source
- Best forMetric-driven Kubernetes canary delivery
- Paid fromFree
- Progressive deliveryYes
- Founded2018
- Facts checked22 Sep 2026
Where it wins
- Automates traffic shifting, promotion, and rollback
- Validates releases with metrics, tests, and webhooks
- Supports meshes, ingress controllers, and observability tools
Where it doesn't
- Requires a self-hosted Kubernetes operating model
- Focused on progressive delivery rather than full CD coverage
- Configuration depends on Kubernetes custom resources
Our verdict on Flagger
Flagger is an open-source Kubernetes operator for teams that want automated control over application releases. It progressively shifts traffic between application versions while measuring service metrics and running conformance, acceptance, or load tests. Deployment strategies include canary, A/B testing with HTTP headers and cookies, blue-green releases, and traffic mirroring. Its intended audience is teams operating applications on Kubernetes, particularly those seeking automated promotion and rollback rather than a hosted continuous delivery service.
Flagger's strongest capability is metric-driven progressive delivery. Built-in checks cover HTTP success rate and latency, while custom metric queries and threshold validation allow release decisions to use service-specific signals. Acceptance tests, load tests, and webhook validation add further gates before promotion. This combination gives platform teams a defined mechanism for validating a release while traffic moves gradually. GitOps integration with Flux CD also connects the operator to a declarative delivery workflow.
Platform fit is broad within the Kubernetes networking and observability ecosystem. Flagger integrates with Istio, Linkerd, Kuma, Gateway API, Contour, Gloo, NGINX, Skipper, Traefik, Apache APISIX, and Knative, plus Prometheus, Datadog, CloudWatch, and New Relic. The trade-off is scope: Flagger specializes in progressive delivery and is configured through Kubernetes custom resources, so teams looking for a wider continuous delivery suite may need a different product. Choose Flagger when Kubernetes traffic control, metric validation, and automated rollback are priorities; choose an alternative when you need a broader delivery platform.
Your product? Our editors can test Flagger in depth and publish a review, labelled as paid · from $149/mo →
Flagger pricing
Flagger fact sheet
| Free plan | Not verified |
|---|---|
| Paid from | Free |
| Pipeline as code | Yes |
| Approval gates | Yes |
| Progressive delivery | Yes |
| Automated rollback | Yes |
| Deployment model | Self-hosted |
| Parallel runs | Not verified |
| Deployment | Self-hosted |
| Support | Community, Docs |
| Built for | Small business, Mid-market, Enterprise (editorial estimate) |
| Integrations | 20 integrations: Istio, Linkerd, Kuma, Knative, Kubernetes CNI, Gateway API … |
| Pricing | Open source |
| Website | flagger.app |
| Facts checked | 22 Sep 2026 |
Flagger integrations
Flagger lists 20 integrations on its own site.
- Istio
- Linkerd
- Kuma
- Knative
- Kubernetes CNI
- Gateway API
- Contour
- Gloo Edge
- NGINX
- Skipper
- Traefik
- Apache APISIX
- Prometheus
- InfluxDB
- Datadog
- New Relic
- CloudWatch
- Graphite
- Slack
- Microsoft Teams
Alternatives to Flagger
- Octopus DeployA mature deployment platform with modeled releases, approvals, rollback, and cloud or self-hosted options.8.9
- Harness Continuous DeliveryBroad deployment coverage, progressive delivery, and governance for large engineering teams.8.8
- Google Cloud DeployA focused managed delivery service for promoting, verifying, and rolling back Google Cloud releases.8.7
See all Flagger alternatives →
Also Ranked In
Flagger is ranked in 4 of our directories.
Used Flagger? Be the first to review it
The editor score above is our own research. What this page doesn't have yet is a reader's view — what you used Flagger for, what worked and what didn't. No stars are seeded and no review is paid for; an editor reads every one before it appears.
Write a reviewTwo minutes · verified accounts only · read by an editor before it appears
Featured on iTechGuides
Flagger is listed in our Continuous Delivery Software directory. Add the badge to your site — it links back to this page.
<a href="https://www.itechguides.com/products/flagger/"><img src="https://www.itechguides.com/best/badge/flagger.svg" alt="Featured on iTechGuides" width="230" height="46"></a>
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
Last updated · How we research and update