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.

Start free Read the integration spec

Who each one is for

Paperkey

Indie devs and AI-native SaaS teams whose first integrator is a coding agent.

MCP server, llms-full.txt, MIT SDKs on npm + PyPI + Packagist. The agent reads the spec and wires it.

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.

  • Model Context Protocol (MCP) server

    Paperkey @paperkeyhq/mcp, 10 tools
    ✓
    Keygen
    ✗
    Cryptlex
    ✗
    Lemon Squeezy
    ✗

  • Single-file LLM integration spec

    Paperkey /llms.txt + /llms-full.txt
    ✓
    Keygen
    ✗
    Cryptlex
    ✗
    Lemon Squeezy
    ✗

  • Public OpenAPI 3.x

    Paperkey /openapi.json
    ✓
    Keygen API reference site
    ◐
    Cryptlex
    ✗
    Lemon Squeezy Public REST docs only
    ◐

  • SDK licence

    Paperkey MIT (npm + PyPI + Packagist)
    ✓
    Keygen MIT (keygen-go, others)
    ✓
    Cryptlex Proprietary
    ✗
    Lemon Squeezy No client SDK
    ✗

  • Self-host option

    Paperkey Docker + Traefik
    ✓
    Keygen Keygen CE (free, OSS)
    ✓
    Cryptlex On-Premise (AWS/Azure/GCP)
    ✓
    Lemon Squeezy Cloud only
    ✗

  • Free tier (no card)

    Paperkey 100 active licenses
    ✓
    Keygen 100 active users + 10 releases
    ✓
    Cryptlex 10 activations, 1 product (perpetual)
    ◐
    Lemon Squeezy Free with checkout
    ◐

  • Signed webhooks

    Paperkey HMAC-SHA-256
    ✓
    Keygen ED25519 / ECDSA / RSA
    ✓
    Cryptlex
    ✓
    Lemon Squeezy
    ✓

  • Offline-tolerant validation

    Paperkey Documented Electron recipe
    ✓
    Keygen Keygen Relay + license files
    ✓
    Cryptlex Built-in (LexActivator)
    ✓
    Lemon Squeezy No native flow
    ✗

  • Native SDKs across many platforms

    Paperkey TypeScript, Python, PHP
    ◐
    Keygen Go, Node, Python, Ruby, PHP…
    ✓
    Cryptlex C++, C#, Java, Go, Python, Rust, Flutter…
    ✓
    Lemon Squeezy JS only
    ◐

  • Bring-your-own checkout (Stripe / Paddle / etc.)

    Paperkey
    ✓
    Keygen
    ✓
    Cryptlex
    ✓
    Lemon Squeezy They ARE the checkout
    ✗

  • Audit / event log

    Paperkey
    ✓
    Keygen
    ✓
    Cryptlex
    ✓
    Lemon Squeezy Limited to order events
    ◐

  • Source available / inspectable

    Paperkey Full monorepo MIT on github.com/paperkeyhq/paperkey. SDKs on npm + PyPI + Packagist.
    ✓
    Keygen Keygen CE is fully OSS
    ✓
    Cryptlex
    ✗
    Lemon Squeezy
    ✗

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.

  • Billing unit

    Paperkey
    Per active license
    Keygen
    Per active licensed user (90-day window)
    Cryptlex
    Per activation
    Lemon Squeezy
    Per transaction (% + flat)

  • Free tier

    Paperkey
    100 active licenses, no card
    Keygen
    Dev tier: 100 ALUs + 10 releases
    Cryptlex
    10 activations, 1 product (perpetual)
    Lemon Squeezy
    Free with checkout

  • Merchant-of-record fee

    Paperkey
    None (BYO checkout)
    Keygen
    None
    Cryptlex
    None
    Lemon Squeezy
    5% + $0.50 per sale (extras stack)

  • Predictable cost as you scale?

    Paperkey
    Yes (per-license tiers)
    Keygen
    Yes (ALU tiers)
    Cryptlex
    Yes (per-activation tiers)
    Lemon Squeezy
    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. The Python and PHP packages have the same surface. 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 MIT-licensed TypeScript, Python and PHP SDKs and a documented Electron / desktop gating recipe. Cryptlex still leads if you need vendor SDKs for many native platforms (C++, C#, Java, Rust, Flutter). 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. 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.

  2. 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.

  3. 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.

Get a migration template Read the API spec

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.

Keygen → Paperkey guide 30-min walkthrough

Ready to swap your licensing layer?

Free tier (100 active licenses). No credit card. Your AI agent can do the wiring.

Start free Read the integration spec

Still evaluating?

Read the 5-minute quickstart. Or skip it: the SDK has decent defaults and the dashboard explains itself.

Open the docs Or just start free →