GrowthBook, Statsig and ConfigCat alternatives

Side by side

Facts are from each vendor's own docs or repository, linked, checked on November 1, 2026. Pricing and plans are left out; check each vendor for what's in which plan. Flagger.gg here is the hosted flag service at flagger.gg, not the Flux/CNCF Flagger.

	GrowthBook	Statsig	ConfigCat	Flagger.gg
Open source	Open core: mostly MIT, with enterprise directories (repo)	Not stated in its docs	SDKs yes; the service no (on-premise FAQ)	No
Hosting	GrowthBook Cloud, or self-hosted with Docker or a Helm chart (self-host)	Hosted	Hosted; an on-premise option and a self-hosted evaluation proxy (proxy)	Hosted only
Evaluation	SDKs download feature definitions, cache them and evaluate in your app (SDKs)	Server SDKs evaluate locally and poll every 10 s by default (server SDKs)	SDKs evaluate locally and send no user data; auto polling every 60 s by default (caching)	Go and Node SDKs evaluate in memory; changes stream in under a second, with 5 s polling if the stream drops
SDKs	Client, server and edge SDKs, from JavaScript and React to Go, Python, Rust and Swift	Server SDKs for Node.js, Java, Python, Go, Ruby, C#, PHP, C++ and Rust (server SDKs)	Over 20, including mobile, Unity and Unreal Engine (SDKs)	Go and Node
Strengths	Warehouse-native experiments with Bayesian or frequentist stats (overview)	Gates, dynamic configs, experiments, product analytics and session replay in one place (session replay)	Targeting with percentage options, segments and prerequisite flags (targeting)	Agent tokens scoped by project, environment and action; approvals with an agent cap; protected flags; per-run audit
MCP server	Hosted (OAuth) or local; four tools that read and write the REST API (docs)	Hosted; 18 default tools, including gate create and update (docs)	Local over stdio; creates, updates and toggles flags (docs)	Hosted at mcp.flagger.gg or `flagger mcp` on stdio; 11 flag tools shown by token scope; no approve tool
CLI	Yes, with `-o json` (docs)	Yes, `siggy`, for gates, configs and experiments (docs)	Yes, with `--json` on several commands (docs)	Yes, `flagger`, with `--json` on every command and exit code 2 for "waiting for approval"

GrowthBook: experiments, and self-hosting

Choose GrowthBook if experimentation is the point. Its analysis runs against your own data warehouse, with Bayesian or frequentist statistics, sequential testing and CUPED, and its docs say no raw user-level events are sent to GrowthBook. It's also the one here you can run yourself: one Docker image with MongoDB, or a Helm chart on Kubernetes. Its SDK list is far broader than Flagger.gg's, covering browser, mobile and edge runtimes.

Flagger.gg doesn't run experiments yet In development, and it's hosted only.

Statsig: flags inside an analytics platform

Statsig combines feature gates with dynamic configs, experiments, product analytics and session replay, and has a warehouse-native option. Its server SDKs evaluate gates locally. Statsig's own blog says it agreed to join OpenAI in September 2025, and a note added since says Amplitude acquired Statsig on May 5, 2026, with the product, brand and customers now part of Amplitude (Statsig).

Pick Statsig if you want flags and product analytics together. Pick a dedicated flag service, Flagger.gg among them, if you only need flags and already have analytics elsewhere.

ConfigCat: many SDKs and rich targeting

ConfigCat is a focused flag service with open-source SDKs in over 20 languages, including mobile and game engines, and targeting rules with percentage options, segments and prerequisite flags. Its SDKs evaluate locally and send no user data to ConfigCat. If you need a self-hosted setup, it offers an on-premise version and a proxy you run in your own infrastructure.

Flagger.gg has five states (off, admins, targets, percent and on), with targeting by user id, verified email and workspace. Segments and richer targeting are In development.

When AI agents ship your code

All three publish MCP servers and CLIs, so an agent can change flags in any of them. Flagger.gg is built around the guardrails for that:

A token per agent, scoped to one project, a list of environments and the actions read create target rollout kill request, expiring after 90 days.
MCP tools listed only when the token's actions allow them, and no approve tool, so an agent can't approve its own change.
A note on every agent write, with the run (thread or job) recorded in the audit log.
An approvals mode in which agents roll out up to a cap in production, 10% by default, and a person approves anything wider.
Protected flags that agents can only kill, and a kill that is never rate-limited.

It's built from the flag system that runs Sandboxer and Transformer in production, from North Bay Ventures.

FAQ

What's an alternative to GrowthBook for feature flags?

If you don't need experiments, a dedicated flag service: ConfigCat for broad SDK coverage and targeting, an open-source tool like Unleash or Flagsmith if you must self-host, or Flagger.gg if AI agents ship your code in Go or Node.

What's a Statsig alternative?

For experiments, GrowthBook or LaunchDarkly. For flags with product analytics, PostHog. For flags alone, ConfigCat, Unleash or Flagsmith, or Flagger.gg if agents write your code.

Is ConfigCat open source?

ConfigCat's docs say its core SDKs are open source and the service itself is not.

Which of these can I self-host?

GrowthBook, with Docker or Kubernetes, and ConfigCat through its on-premise version. Flagger.gg is hosted only, though its SDKs evaluate flags inside your app, so your users are never sent to Flagger.gg.

Do GrowthBook, Statsig and ConfigCat have MCP servers?

Yes. GrowthBook's is hosted or local, Statsig's is hosted and ConfigCat's runs locally over stdio. Flagger.gg's is hosted or stdio, with 11 tools gated by agent-token scope.