Open data API and MCP server

The facts from the guide as JSON, and as an MCP server for Claude, ChatGPT and other AI assistants. Free, no key, read-only.

267 tools
25 categories
CC BY 4.0

JSON API

Base address https://stackwijs.com/api/v1. Every response is JSON with license, attribution and data. CORS is open, so you can also call the API from the browser. The data itself is in Dutch: ids, categories and values such as "ja" (yes), "nee" (no) and "onbekend" (unknown).

Address	What you get
`GET /api/v1/tools`	All tools, best Netherlands check first. Filters: categorie, nl, eu and q (see below).
`GET /api/v1/tools/<id>`	One tool with all public facts, e.g. /api/v1/tools/moneybird.
`GET /api/v1/categorieen`	All categories, with the number of tools and the points of the Netherlands check that count there.

Filter	Meaning
`categorie`	Id of a category, e.g. boekhouding (accounting) or crm. Ids are in Dutch.
`nl`	1: support in Dutch. 0: confirmed no Dutch support.
`eu`	1: data in the EU. 0: confirmed not in the EU.
`q`	Search words; every word must appear in the name, description, category or integrations.

curl 'https://stackwijs.com/api/v1/tools?categorie=boekhouding&nl=1&eu=1'
curl 'https://stackwijs.com/api/v1/tools/moneybird'
curl 'https://stackwijs.com/api/v1/categorieen'

A response looks like this (shortened):

{
  "license": { "name": "CC BY 4.0", "url": "https://creativecommons.org/licenses/by/4.0/deed.nl" },
  "attribution": "Bron: Stackwijs (https://stackwijs.com)",
  "count": 1,
  "data": [{
    "id": "…", "name": "…", "url": "https://stackwijs.com/nl/tool/…", "website": "https://…",
    "category": "boekhouding",
    "pricing": { "from": 12.5, "exclVat": true, "freePlan": false, "trialDays": 30, "note": null },
    "facts": { "nlSupport": true, "dataInEU": null, … },
    "nlCheck": { "score": 6, "total": 7, "points": { "nlSupport": "ja", "dataInEU": "onbekend", … } },
    "keurmerken": ["NL-support", "iDEAL"], "integrations": ["Mollie"],
    "checkedAt": "2026-11-03", "awards": []
  }]
}

null or "onbekend" means we could not verify it on the vendor's website; that is not a no. Prices are per month, in euros, as stated by the vendor (exclVat says whether that is excl. VAT). If you want everything at once, fetch /data/stackwijs-v1.json; for spreadsheets there is also the CSV.

Responses may be cached for 5 minutes. There is a limit of about 60 requests per minute per IP address; above that you get 429 with Retry-After. The data changes at most a few times a day, so feel free to cache.

MCP server

Address https://stackwijs.com/mcp, via Streamable HTTP (JSON-RPC 2.0). No login needed. The server offers four tools:

Tool	What it does
`search_tools`	Search by word, category, Dutch support and data in the EU.
`get_tool`	All facts of one tool.
`list_categories`	The categories of the guide.
`compare_tools`	2 to 4 tools side by side, with the differences as sentences.

Add to Claude

In Claude (web or desktop), go to Settings › Connectors and choose "Add custom connector". Give it a name, for example Stackwijs, and paste https://stackwijs.com/mcp as the address. No authentication is needed. You can then ask questions such as "Which accounting packages have Peppol and data in the EU?".

In Claude Code:

claude mcp add --transport http stackwijs https://stackwijs.com/mcp

Add to ChatGPT

In ChatGPT, turn on developer mode under Settings › Apps and connectors › Advanced. Then create a new connector with https://stackwijs.com/mcp as the address and choose "No authentication". Which subscriptions support this and what the menus are called changes now and then; if in doubt, check OpenAI's help pages.

Call it yourself

curl https://stackwijs.com/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"search_tools","arguments":{"query":"peppol","nl":true}}}'

Licence

The data is licensed under CC BY 4.0. You may use it, commercially as well, if you name Stackwijs as the source and link to the tool's page (the url field), for example: "Source: Stackwijs". Logos belong to the vendors and are not covered by this licence.

The API shows the same facts as the website. A tool cannot pay for a different position in the results, and affiliate links are not in the data.