Ecwid by Lightspeed vs Medusa API + MCP

Ecwid by Lightspeed

The REST API has 40 access scopes, a published limit of 600 requests a minute per token with Retry-After on a 429, field selection through responseFields, and Markdown docs with an llms.txt index. Tokens never expire, there is no test mode or idempotency key, API access needs a paid plan, and carts are built only in the browser.

Medusa API + MCP

MIT core you can self-host, with Medusa Cloud running the same APIs and no GMV fee. The official MCP server is docs-only and limited to Cloud accounts.

Ecwid by Lightspeed

1. Send the token as Authorization: Bearer to https://app.ecwid.com/api/v3/{storeId}. Tokens in the query string stopped working in March 2025
2. Use the secret token server-side only. The public token reads enabled products and places orders that are not marked paid
3. Add responseFields, for example total,items(id,name,price), to keep responses small, and page with offset and limit (maximum 100)
4. Stay under 600 requests a minute per token and wait the Retry-After seconds on a 429. Repeated calls with a bad token get the token and IP blocked for longer
5. Work in a separate test store. There is no test mode, and POST /orders writes a real order with no idempotency key
6. After changing an app's scopes, uninstall and reinstall it, then replace the stored tokens. The old ones stop working

Medusa API + MCP

1. Send x-publishable-api-key on every /store call. It decides which sales channels and products the agent sees
2. Ask for only the fields you need with fields. Store routes reject relations nested more than three deep since 2.20.0
3. Read the store's regions before creating a cart, since prices and shipping options depend on region
4. Place the order with POST /store/carts/{id}/complete after shipping and payment sessions are set
5. Read the release notes before upgrading a minor version. Breaking changes land there