Search and read Sellsy companies, contacts, opportunities, invoices and tasks; create records. Hosted by usefulapi — connect from Claude, ChatGPT, Cursor, or any MCP client.
Team and Enterprise: an Owner adds the connector for the organization first.
Run this command, then run /mcp in Claude Code to log in:
Add to Cursor or add this to ~/.cursor/mcp.json:
{
"mcpServers": {
"sellsy": {
"url": "https://sellsy.usefulapi.io/mcp"
}
}
}Add to VS Code or add this to .vscode/mcp.json:
{
"servers": {
"sellsy": {
"type": "http",
"url": "https://sellsy.usefulapi.io/mcp"
}
}
}No Add custom MCP server option? It depends on your account or workspace settings: see OpenAI's guide.
Run these commands. The second one opens the login page:
Other MCP clients (Windsurf, Cline, Zed and more): add the URL as a remote MCP server (Streamable HTTP). The client then opens the login page in your browser. Do not add an Authorization header: see Before you connect.
The login page asks for your Client ID and Client secret.
In Sellsy open Settings → Developer portal → API V2, create a client of type Personal and tick the scopes you want to use (staffs: read is required to identify your account; for example also companies, contacts, opportunities, estimates, invoices, items, tasks, comments: read, plus write for the records you want to create). The client acts with the rights of your own Sellsy user and reaches your customers’ names, emails and invoices. Your credentials are used only to call the Sellsy API on your behalf and to derive a private account id from your Sellsy account; they are never shown to anyone.
Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Client ID and Client secret. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
Turn on the Sellsy connector, then ask in plain words. The AI picks the tools.
| Tool | Type | What it does |
|---|---|---|
sellsy_search | read | Search across Sellsy Free-text search over companies, individuals, contacts, opportunities, items, documents and staff in one call (GET /search). Use it to find a record by name, email or number when you do not know its type. Needs the search.read scope. |
sellsy_list_companies | read | List companies List companies (customers, prospects, suppliers) with paging. Needs companies.read. |
sellsy_search_companies | read | Search companies Search companies by name, email, type (prospect/client/supplier), reference, VAT, SIRET, country, postal code, creation or update date. Needs companies.read. |
sellsy_get_company | read | Get a company Get one company by id. Needs companies.read. |
sellsy_list_company_contacts | read | List a company's contacts List the contacts linked to one company (GET /companies/{id}/contacts). Needs companies.read and contacts.read. |
sellsy_list_individuals | read | List individuals List individuals (private customers, prospects, suppliers) with paging. Needs individuals.read. |
sellsy_search_individuals | read | Search individuals Search individuals by name, email, type, reference, country, postal code, creation or update date. Needs individuals.read. |
sellsy_get_individual | read | Get an individual Get one individual by id. Needs individuals.read. |
sellsy_list_contacts | read | List contacts List contacts (people at companies) with paging. Needs contacts.read. |
sellsy_search_contacts | read | Search contacts Search contacts by last name, email, phone, linked company or individual, creation date. Needs contacts.read. |
sellsy_get_contact | read | Get a contact Get one contact by id. Needs contacts.read. |
sellsy_list_opportunities | read | List opportunities List sales opportunities with paging. Needs opportunities.read. |
sellsy_search_opportunities | read | Search opportunities Search opportunities by name, number, pipeline, step, status (open/won/lost/cancelled/closed/late), amount, owner or due date. Needs opportunities.read. |
sellsy_get_opportunity | read | Get an opportunity Get one opportunity by id. Needs opportunities.read. |
sellsy_list_opportunity_pipelines | read | List opportunity pipelines List the sales pipelines (needed to create an opportunity: pipeline id and step id). Needs opportunities.read. |
sellsy_list_pipeline_steps | read | List the steps of a pipeline List the steps of one opportunity pipeline. Needs opportunities.read. |
sellsy_list_estimates | read | List estimates List estimates (quotes) with paging. Needs estimates.read. |
sellsy_search_estimates | read | Search estimates Search estimates by status, number, date, currency, owner, contact or related company/individual/opportunity. Needs estimates.read. |
sellsy_get_estimate | read | Get an estimate Get one estimate by id, with its rows and amounts. Needs estimates.read. |
sellsy_list_invoices | read | List invoices List invoices with paging. Needs invoices.read. |
sellsy_search_invoices | read | Search invoices Search invoices by status (draft/due/payinprogress/paid/late/cancelled), number, date, currency, owner, or related company/individual/opportunity. Use it for unpaid or late invoices. Needs invoices.read. |
sellsy_get_invoice | read | Get an invoice Get one invoice by id, with its rows, amounts and status. Needs invoices.read. |
sellsy_list_invoice_payments | read | List an invoice's payments List the payments linked to one invoice. Needs invoices.read and payments.read. |
sellsy_list_orders | read | List orders List orders with paging. Needs orders.read. |
sellsy_search_orders | read | Search orders Search orders by status or delivery status, or related company/individual/opportunity. Needs orders.read. |
sellsy_get_order | read | Get an order Get one order by id. Needs orders.read. |
sellsy_list_credit_notes | read | List credit notes List credit notes with paging. Needs credit-notes.read. |
sellsy_get_credit_note | read | Get a credit note Get one credit note by id. Needs credit-notes.read. |
sellsy_list_items | read | List items List catalog items (products, services, shipping, packaging) with paging. Needs items.read. |
sellsy_search_items | read | Search items Search catalog items by name, reference or type. Needs items.read. |
sellsy_get_item | read | Get an item Get one catalog item by id. Needs items.read. |
sellsy_search_payments | read | Search payments Search payments by status (pending/confirmed/rejected/failed/refund) or related company/individual. Needs payments.read. |
sellsy_list_tasks | read | List tasks List tasks with paging. Needs tasks.read. |
sellsy_search_tasks | read | Search tasks Search tasks by status (todo/done), owner, assignee, label, due date or related record. Needs tasks.read. |
sellsy_get_task | read | Get a task Get one task by id. Needs tasks.read. |
sellsy_list_task_labels | read | List task labels List the task labels (a label id is required to create a task). Needs tasks.read. |
sellsy_search_comments | read | Search comments (notes) Search comments and notes by author, date, parent comment or the company/individual/contact they are attached to. Needs comments.read. |
sellsy_list_staffs | read | List staff members List the staff members of the account (the list may hold only yourself, depending on the Sellsy plan). Needs staffs.read. |
sellsy_create_company | write | Create a company WRITE: create a company record in Sellsy (a prospect, client or supplier). Needs companies.write. Nothing is sent to the company. |
sellsy_create_individual | write | Create an individual WRITE: create an individual (a private person as prospect, client or supplier) in Sellsy. Needs individuals.write. |
sellsy_create_contact | write | Create a contact WRITE: create a contact (a person) in Sellsy. It is not linked to a company by this call. Needs contacts.write. |
sellsy_create_opportunity | write | Create an opportunity WRITE: create a sales opportunity linked to a company, individual or contact. Needs a pipeline id and one of its step ids (see sellsy_list_opportunity_pipelines and sellsy_list_pipeline_steps). Needs opportunities.write. |
sellsy_create_comment | write | Add a comment (note) WRITE: add a comment (note) to a company, individual, contact, opportunity or document. Visible to the Sellsy staff, not sent to the customer. Needs comments.write. |
sellsy_create_task | write | Create a task WRITE: create a task, optionally attached to a record and assigned to staff. Needs a label id (see sellsy_list_task_labels) and a due date-time. Needs tasks.write. |
sellsy_usage_status | Usage status (free-tier meter) Report the caller's current usage: the plan, calls used this month, the limit of the plan (the free monthly cap or the Pro fair use limit), remaining, and whether the limit is reached. Read-only; does not count against the meter. | |
sellsy_request_feature | Request a missing feature Tell usefulapi that the user needs something the Sellsy tools cannot do yet (a missing tool, field or filter). Call it only when the user asks for something none of the tools can do, and tell the user that you send the request. Do not call it for errors or for normal requests. Do not include personal data, credentials or customer records. Stored with the product name and the client type (for example Claude or Cursor), without the user's account. At most 5 requests per day. Does not count against the meter. | |
sellsy_upgrade | Upgrade to Pro (unlimited*) Get Pro: unlimited tool calls (fair use limit: 10,000 a month) on Sellsy (the free tier caps monthly usage). Plans: "monthly" — $9/month; "yearly" — $90/year (2 months free). Cancel any time: Pro then runs to the end of the paid period, so it also suits a one-time job. *A fair use limit applies. For heavy use (near Pro's limit): "plus" or "plus_yearly" — Pro+, $39/month or $390/year, unlimited tool calls (fair use limit: 100,000 a month); an existing Pro subscription changes to Pro+ in place (needs confirm: true; the price difference for the rest of the period is charged at once). Otherwise returns a short link to open in your browser (it opens Stripe Checkout); after payment the account upgrades automatically. Does not count against the meter. | |
sellsy_cancel_subscription | Cancel the Pro subscription Cancel the caller's Sellsy Pro subscription at the end of the paid period (no refund for the current period; Pro continues until then, then the free tier applies). Requires confirm: true. Run sellsy_upgrade later to undo the cancel before the period ends. Does not count against the meter. |
| Plan | Price | Limit |
|---|---|---|
| Free | $0 | 50 tool calls / month |
| Proper account | $9/mo · $90/yr | Unlimited* |
*Pro fair use limit: 10,000 tool calls a month on this server. For more, write to [email protected].
Pro covers this Sellsy server only. Subscribe with sellsy_upgrade (it returns a Stripe Checkout link). Cancel any time with sellsy_cancel_subscription: Pro continues to the end of the paid period, with no refund for the current period, and running sellsy_upgrade before then undoes the cancel. Or write to [email protected].
No. usefulapi is an independent service. It is not affiliated with or endorsed by Sellsy. The server calls the Sellsy API with your own Sellsy access, so it sees only the data that your account can see.
Yes. In Claude, add this server's URL as a custom connector. In ChatGPT, add it as a custom MCP server in Plugins. Then log in once. Cursor, VS Code, Claude Code and Codex work too. See the setup steps.
The login page asks for your Client ID and Client secret. See Before you connect for where to find them.
No. Add only the URL. Do not add an Authorization header or an API key to the client config. The server signs you in with OAuth: the login page asks for your Client ID and Client secret. If the config has such a header, remove it: some clients then send that header instead of the login token, and every call fails with 401.
The login stores them encrypted in the authorization grant of your connection. The server uses them to call the Sellsy API for you and to derive a private account id for usage metering. usefulapi does not show them on any page or in any reply. To stop all access, remove the connector and change or delete these credentials in Sellsy.
Yes, if you approve it. 6 of the 44 Sellsy tools can create or change data. The other 38 are marked read-only. Most MCP clients ask you to approve a tool call before it runs.
The Free plan gives 50 tool calls / month. Pro costs $9/mo or $90/yr, with unlimited tool calls (fair use limit: 10,000 tool calls a month), for this Sellsy server only. Cancel any time: Pro then runs to the end of the paid period. Run sellsy_usage_status to see how many calls you used.
Ask the AI to run sellsy_upgrade: it returns a Stripe Checkout link. To cancel, run sellsy_cancel_subscription. Pro continues to the end of the paid period.
Tell the AI what you wanted to do. It can send the request with sellsy_request_feature. We store the text with the server name, the type of AI client and the tool you tried, not with your account, and read every request when we plan new tools. You can send up to 5 requests per day.
Any client that supports remote MCP servers (Streamable HTTP) with OAuth login: Claude (web and desktop), Claude Code, ChatGPT, Codex, Cursor, VS Code, Windsurf and others.
This is a Model Context Protocol endpoint — meant to be connected from an AI client, not opened in a browser. An invalid_token response at the URL is the auth gate working as designed; clients authenticate automatically.