Polar
Open-source merchant-of-record billing platform built for developers. Subscriptions, usage metering, and digital product sales with global tax handling and a 100% free starter plan.
Use Cases
Free Tier
Free Starter plan — 5% + 50¢ per transaction, no monthly fee, all selling features included
How to Maximize the Free Tier
Polar's Starter plan is genuinely free: no monthly fee, no setup cost, and all selling features included — you only pay 5% + 50¢ per transaction, which covers merchant-of-record tax handling in 100+ markets. That makes it a Lemon Squeezy-style alternative with a zero-cost floor. Watch the per-transaction fee if you sell low-priced items — at a $5 product the 50¢ fixed component eats 10% of your margin. Pro tip: Polar is built for AI-era billing with native usage metering (tokens, API calls, GPU seconds), so if you're selling an API or AI wrapper you can meter and bill without a separate usage platform. Its open-source core means you can self-host or audit the code. Combine with a free checkout-link approach for one-off digital products, and use their payout scheduling to control cash flow. The Startup Program gives 12 months free on the Scale plan for early-stage AI startups.
Getting Started
Sign up at polar.sh with GitHub → create an organization → add a product (subscription, usage meter, or one-time digital product) → configure pricing and checkout → integrate via API, SDK, or hosted checkout links → test with a sandbox purchase → go live and connect your payout bank account → monitor revenue and usage in the dashboard.
Pros
- Free starter plan: $0/month with all selling features and no setup cost — pay only when you make a sale
- Usage metering built in: Native token/API-call/compute metering means AI products can bill by usage without a second platform
- Open source: The core platform is open source (github.com/polarsource) — auditable, and self-hosting is on the roadmap
Cons
- Transaction fee: 5% + 50¢ per transaction is higher than direct processors like Stripe (2.9% + 30¢) — best for products with healthy margins
- Newer platform: Smaller ecosystem and fewer third-party integrations than Stripe or Paddle; docs are still maturing
- Approval process: Merchant-of-record onboarding requires business verification before you can sell live