Polar: The Open-Source Merchant of Record That Handles Your International Tax Compliance

You built something developers want. Now you need to charge for it. Stripe handles the payment — but who handles VAT in Germany, GST in Australia, sales tax across 50 US states? Every global sale potentially creates a tax obligation in a jurisdiction you've never thought about.

Polar solves this as a Merchant of Record. Polar is the legal seller of record — they collect payments, handle tax calculation and remittance in 60+ countries, and pay you out. You build. Polar handles the compliance infrastructure that otherwise requires a lawyer or an accountant.

What Polar is

Polar (polar.sh) is an open-source developer monetization platform acting as a Merchant of Record. Founded 2021 in Sweden, YC W23, Apache 2.0 licensed. Built on top of Stripe. Fully public codebase — you can read exactly how Polar handles tax collection, webhook delivery, and subscription state.

2026 positioning: "billing platform for the intelligence era" — AI SaaS and usage-based billing are first-class, not workarounds.

What Polar sells for you

Subscriptions — monthly/annual with trials, proration, and seat-based pricing. Customer portal for self-service changes — no custom UI needed from you.

One-time products — licenses, digital downloads, templates, delivered automatically on purchase via webhook or SDK.

Usage-based billing — meter API calls, tokens, compute time, or any custom unit. Report events via API, Polar aggregates and bills at period end. Built for AI SaaS: per-token pricing, inference cost pass-through, usage caps.

License keys — generated automatically on purchase, verifiable via API. Built-in, not a third-party add-on.

GitHub Sponsors integration — unique: no other MoR offers this natively. Connect your repo and Polar appears as an official funding option on your GitHub sidebar. Community members can also fund specific GitHub issues — developers get paid for resolving them.

Affiliate program — built-in affiliate link generation, commission tracking, and payouts.

API and SDK

import { Polar } from "@polar-sh/sdk";
const polar = new Polar({ accessToken: process.env.POLAR_ACCESS_TOKEN });

// Create a checkout session
const checkout = await polar.checkouts.create({
  productId: "prod_xxx",
  successUrl: "https://yourapp.com/success",
  customerEmail: user.email,
});

// Report usage for metered billing
await polar.usage.report({
  customerId: user.polarCustomerId,
  eventName: "api_call",
  amount: 1,
  metadata: { model: "gpt-4o", tokens: 1240 },
});

SDKs in TypeScript, Python, and Go. Public OpenAPI spec. Webhooks cover every billing event with reliable retry logic.

Pricing

Starter has no monthly fee — you pay only when you earn. The math shifts toward Pro around $1,500–2,000 MRR. The delta between Polar's fee and Stripe's 2.9% + $0.30 is essentially the cost of outsourcing international tax compliance.

Polar vs Lemon Squeezy vs Stripe direct

vs Lemon Squeezy — both are developer-focused MoRs at similar pricing. Polar wins on: open source codebase, native GitHub Sponsors integration, and first-class usage-based billing. Lemon Squeezy wins on: longer track record, some integrations not yet in Polar.

vs Stripe direct — Stripe is cheaper per transaction (2.9% + $0.30) but you carry the full global tax compliance burden yourself. Polar makes sense when you're selling globally and don't want to manage VAT/GST obligations across dozens of jurisdictions.

Who it's for

Good fit: open source maintainers who want GitHub Sponsors + subscriptions + issue funding in one place; indie developers and solo SaaS founders selling globally without international tax headaches; AI SaaS products needing per-token or per-call billing; developer tools needing built-in license key management.

Not ideal: high-volume SaaS where Stripe direct + TaxJar is cheaper at scale; physical goods (Polar is digital only); teams needing deep ERP integrations not yet supported.

My take

International tax compliance is a solved problem for companies with finance teams and a nightmare for solo developers. The MoR model is genuinely valuable. The GitHub Sponsors and issue funding integration is the differentiator no other MoR has — if you maintain an open-source project with meaningful GitHub traffic, Polar is the obvious choice over GitHub Sponsors alone.

The open source codebase matters for trust. When Polar handles your money, you can read exactly how they do it. That's a meaningful difference from black-box MoR providers.