Now in public beta

Ship features without fear

Feature flags API that fits in one curl command. Targeting rules, percentage rollouts, instant kill switches — all through a simple REST API. No SDK bloat. No vendor lock-in.

Start for free → Try the demo

No credit card required · 1,000 evaluations/day free

evaluate.sh

curl -X POST https://flagbit.anethoth.com/api/v1/evaluate \
  -H "Authorization: Bearer fbsdk_your_key" \
  -d '{"flags": ["new_checkout", "dark_mode"],
      "context": {"country": "US", "plan": "pro"}}'

# Response:
{
  "flags": {
    "new_checkout": "true",
    "dark_mode": "true"
  }
}

Works with any stack

▸ curl / REST ▸ Node.js ▸ Python ▸ Go ▸ Ruby ▸ PHP ▸ Java

Everything you need to ship safely

No config files, no SDKs to install, no deploy pipelines to modify. Just API calls.

Instant Rollouts

Toggle features on or off instantly. No deploys. No waiting. One API call and your feature is live — or not.

User Targeting

Target by country, plan, user ID, email domain, or any custom attribute. Rules evaluate server-side in <5ms.

Percentage Rollouts

Roll out to 5%, then 25%, then 100%. Consistent hashing ensures users always get the same experience.

Kill Switches

Something goes wrong? Disable any feature instantly. No rollback deploy needed. Just flip the flag.

Multi-Project

Separate flags by project with unique SDK keys. Microservices, monorepos, mobile + web — all organized.

REST-First

No proprietary SDK required. Plain REST API works from any language, any platform, any framework. Just HTTP.

Live in 60 seconds

Three API calls. That's it.

Create a flag

POST a flag with a key, targeting rules, and default value. Done.

POST /api/v1/projects/1/flags

{"key": "new_checkout", "enabled": true}

Evaluate in your app

Call the evaluate endpoint with user context. Get back flag values.

POST /api/v1/evaluate

{"sdk_key": "fbsdk_...", "context": {"plan": "pro"}}

Toggle anytime

Enable, disable, or change rules with a single PUT. Instant effect.

PUT /api/v1/projects/1/flags/new_checkout

{"enabled": false}

Try it right now

Evaluate feature flags with custom context — no signup required

User Context

Country

User ID

Plan

Flag Results

dark_mode —

new_checkout —

beta_feature —

Simple, honest pricing

Start free. Upgrade when you need more.

Free

$0/mo

For side projects

✓ 1 project
✓ 10 flags
✓ 1K evals/day
✓ Targeting rules

Get started

Popular

Starter

$9/mo

For growing teams

✓ 5 projects
✓ 50 flags/project
✓ 50K evals/day
✓ % rollouts

Start trial

Pro

$29/mo

For scaling products

✓ 20 projects
✓ 200 flags/project
✓ 500K evals/day
✓ Priority support

Start trial

Business

$49/mo

For teams at scale

✓ 100 projects
✓ 1000 flags/project
✓ 5M evals/day
✓ SLA + priority

Why FlagBit over the alternatives?

	FlagBit	LaunchDarkly	Unleash
Starting price	Free / $9/mo	$10/seat/mo	Free (self-host)
Setup time	60 seconds	30+ minutes	Hours (Docker)
SDK required?	No — pure REST	Yes	Yes
Targeting rules	✓	✓	✓
Per-seat pricing?	No — flat rate	Yes	Yes (paid)

Frequently asked questions

How fast is the evaluate endpoint?

Typically under 5ms. Flag evaluation is done in-memory with no external calls. The API overhead is usually the network round-trip, not the computation.

Do I need to install an SDK?

No. FlagBit is a pure REST API. Use curl, fetch, axios, or any HTTP client. Works from any language or platform without installing anything.

How do percentage rollouts work?

We hash the user attribute (e.g., user_id) consistently, so the same user always gets the same result. Set a percentage rule and it'll apply to that fraction of your users deterministically.

What happens if my app can't reach FlagBit?

Always use a local default in your code: if (flag == "true") with a sensible fallback. Feature flags should degrade gracefully — if the API is unreachable, your app should still work with defaults.

Can I self-host FlagBit?

Not yet. We're considering an open-source edition in the future. For now, the hosted version is the simplest way to get started — no infrastructure to manage.

How does billing work?

Monthly subscription via Stripe. Upgrade or downgrade anytime. No contracts, no hidden fees. The free tier doesn't require a credit card.