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Flags SDK

Free open-source Vercel library for Next.js and SvelteKit feature flags. Framework-native, provider-agnostic with adapters for LaunchDarkly, Statsig, Optimizely, Hypertune, ConfigCat, DevCycle and Flipt.

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Our Verdict

Essentially required glue for feature flags in Next.js; pair it with a real flag provider of your choice.

Pros

  • Framework-native for Next.js and SvelteKit
  • Provider-agnostic with adapters for major flag SaaS
  • Free and open source
  • Handles server/edge evaluation cleanly

Cons

  • Only a client/framework layer; you still need a provider
  • Best DX when also hosting on Vercel
  • Limited value outside Next/SvelteKit
  • Some adapters lag upstream feature parity
Best for: Next.js/SvelteKit teams integrating existing flag SaaS cleanly Not for: Non-Vercel stacks or teams needing the provider itself

When to Use Flags SDK

Good fit if you need

  • Framework-native feature flags for Next.js and SvelteKit
  • Provider-agnostic adapters for LaunchDarkly and Statsig
  • Edge-compatible flag evaluation without latency penalty
  • A/B testing built into Vercel deployment previews

Lock-in Assessment

Low 5/5
Lock-in Score
5/5

Flags SDK Pricing

Pricing Model
free
Free Tier
Yes
Entry Price
Enterprise Available
No
Transparency Score

Beta — estimates may differ from actual pricing

1,000
1001K10K100K1M

Estimated Monthly Cost

$25

Estimated Annual Cost

$300

Estimates are approximate and may not reflect current pricing. Always check the official pricing page.

Project Health

C

Health Score

586 70
Bus Factor

3

Last Commit

3 days

Release Freq

6d

Open Issues

21

Issue Response

N/A

License

MIT

Last checked: 2026-04-21

Community Discussion

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