--- title: "Sellsy API: connect it to your AI chat ยท Hypamoon" description: "The Sellsy API is open, signs in with OAuth client credentials and sends webhooks. What your AI chat can build with it on Hypamoon, with sources." url: https://hypamoon.com/connect-to/sellsy --- 1. [Connect to](https://hypamoon.com/connect-to) 2. Sellsy CRM # Connect Sellsy to Hypamoon Yes, with one catch. Sellsy has an open API that you can use yourself, but it signs in with OAuth only, and that takes more work in a Hypamoon adapter today. Open ## The check Three questions about the API of Sellsy, answered from its own docs. **Public API docs**\ **Yes.** Public API v2 reference with authentication, quotas and versioning. [Read the docs](https://docs.sellsy.com/api/v2/) **A key you create yourself**\ **Yes.** You create an OAuth client yourself on the developer page of your account; a personal client may use the client credentials flow. [docs.sellsy.com](https://docs.sellsy.com/api/v2/) **Versions or a changelog**\ **Yes.** Numbered releases in a dated changelog, and the API is versioned. [docs.sellsy.com](https://docs.sellsy.com/api/v2/changelog.html) **How it signs in**\ A personal OAuth client gives a bearer access token through client credentials; the token lasts 24 hours and is then requested again. **Webhooks**\ **Yes.** It can tell your app when something changes. [docs.sellsy.com](https://docs.sellsy.com/api/v2/) **Hosting**\ Cloud ## Your own sales and customer tools on Sellsy, shaped around your pipeline. - Companies, contacts, opportunities, quotes and invoices, straight from Sellsy. - AI that reads new leads and suggests the next step for the sales team. - A screen for the team and a weekly email for you. ### Ask your chat Answers straight from your Sellsy data, in Claude or another chat with the full Hypamoon connection. - Which opportunities have had no activity in the last two weeks? - Which quotes over 5,000 euros are still open? ### When something happens Sellsy sends a webhook to your app, and the app asks AI what happens next. 1. When A new opportunity is created in Sellsy. AI decides AI looks at the company and the source and suggests a priority and a first message. Then The owner of the opportunity gets an email with the suggestion. ### A screen for your team or customers An app on your own address, with sign-in, on top of the same Sellsy data. - For your team A screen with the pipeline per salesperson and the quotes waiting for an answer. ### Add Hypamoon Text messages, email, phone, payments and agents run in the same project as the adapter. - Agent on a schedule Every Monday, an agent emails you the deals that went quiet. Sellsy stays the core: your chat builds the rest on its API, as an adapter plus an app and agents in your Hypamoon project. Reading starts after you click Allow in the portal. Every change an agent or a chat makes in Sellsy waits for your approval, one call at a time. [How adapters work](https://hypamoon.com/docs/adapters) ### Good to know - Sellsy signs in with OAuth or signed requests only, with tokens that expire. The Hypamoon vault holds a fixed key today, so an adapter for Sellsy takes more work: ask your chat to check this first. - Quotas apply per account per second, minute, day and month; the remaining quota is in the response headers. ## Try it in your chat Fill in what to read and write, and send it. Say this in your chat > Build the Hypamoon recipe build-an-adapter for Sellsy. API docs: https://docs.sellsy.com/api/v2/. Read: \[what\]. Write: \[what, or nothing\]. [Open in Claude](https://claude.ai/new?q=Build%20the%20Hypamoon%20recipe%20build-an-adapter%20for%20Sellsy.%20API%20docs%3A%20https%3A%2F%2Fdocs.sellsy.com%2Fapi%2Fv2%2F.%20Read%3A%20%5Bwhat%5D.%20Write%3A%20%5Bwhat%2C%20or%20nothing%5D.) In Claude, or another chat with the full Hypamoon connection; adapters are not in ChatGPT yet. You paste the key in the portal, never in the chat. [The full recipe](https://hypamoon.com/r/build-an-adapter) ## Sources Checked on 7 November 2026. - [docs.sellsy.com/api/v2/](https://docs.sellsy.com/api/v2/) - [docs.sellsy.com/api/v2/changelog.html](https://docs.sellsy.com/api/v2/changelog.html) Sellsy is a name of its owner, used here only to describe the software. This page is not an official integration and Hypamoon has no partnership with Sellsy. Found something that changed? 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Ask the chat to check its API. The same three checks work for any software. Your chat reads the vendor's own docs and tells you what it found. Say this in your chat > Check if \[software\] has an open API that a Hypamoon adapter can use: public API docs, a key or token I can create myself without asking the vendor, and versions or a changelog. Link the pages you used. [Open in Claude](https://claude.ai/new?q=Check%20if%20%5Bsoftware%5D%20has%20an%20open%20API%20that%20a%20Hypamoon%20adapter%20can%20use%3A%20public%20API%20docs%2C%20a%20key%20or%20token%20I%20can%20create%20myself%20without%20asking%20the%20vendor%2C%20and%20versions%20or%20a%20changelog.%20Link%20the%20pages%20you%20used.) [Open in ChatGPT](https://chatgpt.com/?q=Check%20if%20%5Bsoftware%5D%20has%20an%20open%20API%20that%20a%20Hypamoon%20adapter%20can%20use%3A%20public%20API%20docs%2C%20a%20key%20or%20token%20I%20can%20create%20myself%20without%20asking%20the%20vendor%2C%20and%20versions%20or%20a%20changelog.%20Link%20the%20pages%20you%20used.) Fill in the name of your software. Checking needs no connection to Hypamoon. ## Ready to connect Sellsy? Connect your chat once, then ask it to build the adapter. [Start free](https://app.hypamoon.com/?mode=signup&utm_source=connect-to&utm_campaign=sellsy) Works in Claude, ChatGPT and Copilot. [Add to Claude](https://hypamoon.com/connect?via=connect-to~sellsy#claude) [Add to ChatGPT](https://hypamoon.com/connect?via=connect-to~sellsy#chatgpt) [Add to Copilot](https://hypamoon.com/docs/microsoft-copilot)