Pricing, limits, and integration
Both the API and the MCP server come with your Systeme.io account, including the free plan (2,000 contacts, unlimited emails). There is no separate agent fee. The practical limit is the API-key model: keys expire every 90 days and you can hold at most two at a time, so long-running automations need a key-rotation reminder until OAuth ships.
The server enforces per-window rate limits via X-RateLimit headers and returns 429 when exceeded, so budget request pacing for high-volume agent loops rather than assuming unlimited calls.
How much does the Systeme.io API actually cost?
Systeme.io publishes an API, but per-tier gating wasn't extracted automatically.
- Most likely scenario: API access is either included in all paid plans, or it's gated to higher tiers and we need to verify on the live docs page.
- Until verified, treat the question "which plan unlocks the API" as open. Don't budget on the assumption it's free with the cheapest paid plan.
API at a glance
Which AI clients can read Systeme.io data?
Not every AI assistant supports MCP natively. Here's the per-client picture for Systeme.io specifically.
| Client | Support | Notes |
|---|---|---|
| Claude (Desktop/Web) | Native MCP | Add https://mcp.systeme.io/mcp?mcpKey=YOUR_KEY as a custom connector; the MCP key is generated free in Systeme.io settings. |
| ChatGPT | Native MCP | Documented by Systeme.io; connect with the same MCP key via ChatGPT's connector settings. |
| Claude Code | Native MCP | claude mcp add --transport http systeme https://mcp.systeme.io/mcp?mcpKey=YOUR_KEY (key passed in the URL or the X-MCP-Key header). |
Systeme.io also has an MCP server
If you're wiring Systeme.io into Claude / Cursor / Codex, the MCP server is usually less code than the REST API.
See Systeme.io MCP pageWhat you can build with the Systeme.io API
Three personas, three different shapes of build. Pick the row that matches how you actually ship.
Glue Systeme.io into your daily workflow
- Pull a digest of fresh activity into your morning Slack
- Trigger a one-off backfill when something looks off
- Pipe data into your own SQLite for ad-hoc queries
Sell Systeme.io reporting at scale
- White-label Systeme.io data into client-branded dashboards
- Run scheduled multi-account reports without logging into the Systeme.io UI
- Cross-reference with the rest of the client's stack (CRM, analytics, ad spend)
Production pipelines for Systeme.io
- Real-time sync into your warehouse via webhooks
- Custom alerts the dashboard's built-in alerting can't express
- Backfill + idempotency handling for Systeme.io data older than the dashboard exposes
Quickstart template
# Starter template — endpoint paths and SDK package names come from # the Systeme.io API docs: https://developer.systeme.io curl -X GET "https://developer.systeme.io/<your-endpoint>" \ -H "Authorization: Bearer $TOKEN" \ -H "Accept: application/json" | jq .
Template only. Endpoint paths, exact base URL, and auth header format come from developer.systeme.io.
Limits and gotchas
- No OpenAPI spec — you write typed clients by hand or use a third-party generator on the docs HTML.
- Webhooks available — react to Systeme.io events in real time instead of polling.
- No official SDK detected. Plan on hitting the API directly with your HTTP client of choice.
- Rate limits: always read the docs page before scaling — the published limit is usually lower than the practical one and overages can be expensive.
- No-code fallback: Zapier cover the common triggers if you want to skip writing API code for simple flows.
Agent-readiness verdict
A clean REST API with API-key auth, webhooks, and an llms.txt docs index, available even on the free plan for core endpoints. It scores 7 out of 10: genuinely accessible and agent-readable, with the missing OpenAPI spec and SDKs the main things separating it from the best-documented APIs.
Official MCP verified 2026-07-08: mcp.systeme.io/mcp, API-key auth (X-MCP-Key header or mcpKey param, 90-day keys, max 2), FREE PLAN, ChatGPT+Claude, contacts/tags/newsletters/opt-in-funnels write tools, rate-limited. OAuth planned. 4->7 Joonas approved.
Systeme.io API FAQ
Does Systeme.io have a public API?+
What auth does the Systeme.io API use?+
Does Systeme.io support webhooks?+
Should I use the API or the MCP server for Claude / Cursor / Codex?+
Sources
- Systeme.io official site: https://systeme.io/
- API docs: https://developer.systeme.io
- MCP server: https://mcp.systeme.io/mcp
10+ years in digital marketing. I review marketing software for AI-stack fit: real pricing, MCP and API support, and how cleanly each tool drops into an AI agent workflow, cross-checked against verified data and real user feedback.