Paperkey
Indie devs and AI-native SaaS teams whose first integrator is a coding agent.
MCP server, llms-full.txt, MIT SDK. The agent reads the spec and wires it.
Alternatives
Paperkey vs Keygen, Cryptlex, Lemon Squeezy
Enterprise suites are built for sales teams. Paperkey is built for devs shipping code. The licensing infrastructure optimized for local-first software (desktop apps, CLI tools, IDE extensions, plugins) with native MCP support for instant AI-assisted integration.
Who each one is for
Keygen
Teams that need a mature, broad licensing API with MIT clients across many languages.
Battle-tested REST, ED25519-signed webhooks, fully OSS Community Edition for self-host.
Visit Keygen →Cryptlex
Native desktop / embedded apps across many platforms (C++, C#, Java, Rust, Flutter).
Polished proprietary SDKs, built-in offline activation, hardware locking.
Visit Cryptlex →Lemon Squeezy
Solo makers who want a single dashboard for checkout AND license keys.
Merchant of record handles tax / refunds, license keys included with checkout.
Visit Lemon Squeezy →Feature comparison
Marks: ✓ supported out of the box, ◐ partial or with caveats, ✗ not in the product.
| Feature comparison | Paperkey | Keygen | Cryptlex | Lemon Squeezy |
|---|---|---|---|---|
| Model Context Protocol (MCP) server | ✓ @paperkeyhq/mcp, 10 tools | ✗ | ✗ | ✗ |
| Single-file LLM integration spec | ✓ /llms.txt + /llms-full.txt | ✗ | ✗ | ✗ |
| Public OpenAPI 3.x | ✓ /openapi.json | ◐ API reference site | ✗ | ◐ Public REST docs only |
| SDK licence | ✓ MIT | ✓ MIT (keygen-go, others) | ✗ Proprietary | ✗ No client SDK |
| Self-host option | ✓ Docker + Traefik | ✓ Keygen CE (free, OSS) | ✓ On-Premise (AWS/Azure/GCP) | ✗ Cloud only |
| Free tier (no card) | ✓ 100 active licenses | ✓ 100 active users + 10 releases | ◐ 10 activations, 1 product (perpetual) | ◐ Free with checkout |
| Signed webhooks | ✓ HMAC-SHA-256 | ✓ ED25519 / ECDSA / RSA | ✓ | ✓ |
| Offline-tolerant validation | ✓ Documented Electron recipe | ✓ Keygen Relay + license files | ✓ Built-in (LexActivator) | ✗ No native flow |
| Native SDKs across many platforms | ◐ TS today, more on roadmap | ✓ Go, Node, Python, Ruby, PHP… | ✓ C++, C#, Java, Go, Python, Rust, Flutter… | ◐ JS only |
| Bring-your-own checkout (Stripe / Paddle / etc.) | ✓ | ✓ | ✓ | ✗ They ARE the checkout |
| Audit / event log | ✓ | ✓ | ✓ | ◐ Limited to order events |
| Source available / inspectable | ◐ MIT SDK + MCP on npm. Full repo public on roadmap. | ✓ Keygen CE is fully OSS | ✗ | ✗ |
Pricing model at a glance
Exact prices change. Check each vendor's pricing page. The shape of how they bill is what matters when you scale.
| Pricing model at a glance | Paperkey | Keygen | Cryptlex | Lemon Squeezy |
|---|---|---|---|---|
| Billing unit | Per active license | Per active licensed user (90-day window) | Per activation | Per transaction (% + flat) |
| Free tier | 100 active licenses, no card | Dev tier: 100 ALUs + 10 releases | 10 activations, 1 product (perpetual) | Free with checkout |
| Merchant-of-record fee | None (BYO checkout) | None | None | 5% + $0.50 per sale (extras stack) |
| Predictable cost as you scale? | Yes (per-license tiers) | Yes (ALU tiers) | Yes (per-activation tiers) | Tied to revenue, not licenses |
Snapshot taken on 2026-04-28. Vendor pricing changes. Verify on each provider's site before buying.
Integration in 30 seconds
Three lines of TypeScript with the SDK. Same shape if you skip the SDK and use raw fetch (see /docs/api).
Why this matters
Your AI agent reads /llms-full.txt, drops the SDK, and wires this snippet into your codebase end-to-end. No reading the docs site by hand.
import { createClient } from '@paperkeyhq/sdk';
const paperkey = createClient({ apiKey: process.env.PAPERKEY_PUBLIC_KEY });
const v = await paperkey.validate(licenseKey, fingerprint);
if (!v.valid) throw new Error(v.error ?? 'invalid_license');Common questions
Is Paperkey a Keygen alternative?
Yes. Paperkey covers the same core surface (issue, validate, activate, deactivate, revoke, signed webhooks) and adds first-class support for AI coding agents through an MCP server and an llms-full.txt spec.
Is Paperkey a Cryptlex alternative?
For most indie and small-team use cases, yes. Paperkey ships an MIT-licensed TypeScript SDK and a documented Electron / desktop gating recipe. Cryptlex still leads if you need vendor SDKs for many native platforms. Paperkey leads if you want an open spec your agent can read.
How does Paperkey compare to Lemon Squeezy license keys?
Lemon Squeezy bundles licensing onto a merchant-of-record checkout. Base fee 5% + $0.50 per sale, with extras that stack (international +1.5%, PayPal +1.5%, subscriptions +0.5%). Paperkey is licensing-only: keep your existing Stripe, Paddle, or merchant of record, and bring Paperkey for the keys with no MoR fee.
Can I migrate existing license keys to Paperkey?
Yes. Issue licenses through POST /licenses with your own keys preserved in the metadata field, or import in bulk. Reach out at hello@paperkey.dev for a migration template.
Does Paperkey self-host?
Yes. The repo ships a Docker + Traefik + distroless setup for a single-VPS deploy. The dashboard, API, and Postgres run side-by-side. See INFRA.md.
What about cost predictability?
Paperkey bills per active license on tiered plans, so cost scales with paying customers. Per-request models can spike if you re-validate aggressively. Merchant-of-record models scale with revenue, not seat count.
Migration
Migrate from Keygen, Cryptlex, or Lemon Squeezy
Three steps. We keep your existing keys so your shipped clients keep validating during the cutover.
-
1. Export from your current vendor
Pull licenses, customer emails, activation counts, and expiration dates as CSV or JSON. The vendor admin panel or its REST API both work.
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2. Import in bulk, keeping your old keys
POST /licenses accepts the original key in the metadata field, so existing installs keep validating without a forced re-key. Issue caps and expirations carry over 1:1.
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3. Cut over webhooks and ship the new SDK
Roll out @paperkeyhq/sdk in your next app release. Point your billing webhooks at Paperkey. The old vendor stays read-only until you decommission it.
Already on Keygen, Cryptlex, or Lemon Squeezy?
Migrate in 10 minutes.
Concept mapping, copy-pasteable bash, known limitations. The SDK in your shipped app stays the same.
Ready to swap your licensing layer?
Free tier (100 active licenses). No credit card. Your AI agent can do the wiring.
Still evaluating?
Read the 5-minute quickstart. Or skip it: the SDK has decent defaults and the dashboard explains itself.