Accredo API guide: Saturn OData and the Mercury web service

Updated 11 November 2026

What the Accredo API is

Accredo's Web Service API is a RESTful OData v4 API that returns JSON. It addresses the whole company file from outside the desktop application: customers, products, invoices, orders, scripts and reports. Accredo introduced it in version 5.

It is the official way to connect another system to Accredo. Rapido's B2B portal, AI processes and integrations all run on it.

Saturn OData and the Mercury web service

You'll see it called "Saturn OData" or "the Mercury web service". It's the same Web Service API. Accredo ships the Saturn and Mercury web services at the same release, and Rapido uses the same SDK and the same code for both.

What differs is the data behind it:

• Saturn handles several locations, branches and departments, so you see branch and department fields and stock held across sites.
• Mercury is aimed at a single location, so those dimensions aren't there.

For the business side of that choice, see Accredo Saturn vs Mercury.

What it covers

The API follows Accredo's modules: Accounts Receivable (AR), Accounts Payable (AP), General Ledger (GL), Banking (CB), Inventory (IC), Order Entry (OE), Purchase Orders (PO), Job Costing (JC) and Fixed Assets (FA), plus Foreign Exchange (FX) where it's licensed. Each module exposes its records as OData entities you can query, create and update.

Beyond plain records, it can also:

• Produce documents. Bound functions return an invoice, order or purchase order as a PDF in your own Accredo form layout.
• Run reports and return the output.
• Run scripts written in MaxBasic, Accredo's scripting language.

The service publishes an OData $metadata document that lists every entity, field and bound function. On Saturn, requests are addressed to a company like this:

GET /Saturn/odata4/v1/Company('<company code>')/$metadata

If a module isn't licensed on your Accredo, its endpoints refuse the request. Check which modules you have before you plan an integration around one.

What you need to start

1. Accredo Saturn or Mercury, version 5 or later. On-premise, Accredo Cloud Hosting, or hosted on Azure or AWS.
2. An API user on your company file. You or your Accredo partner can create it.
3. Network access to the Web Service API from wherever your code runs. If Accredo sits on a server in your office, that usually means your partner or IT opening access to it.
4. A test company if you can get one. Try reads first, and only write once you know what each call changes.

Where people get stuck

• OData is its own language. Filter syntax, expansions, paging and batch requests each work a little differently, and the spec is large.
• Field names don't always match the screens. What a user calls a field in Accredo and what the API calls it are not always the same. Use $metadata.
• Errors are HTTP-shaped. You get a status code and a message, not an Accredo-style prompt, so build in logging from the start.
• Printing has side effects. If you only want a PDF, use the preview function. The print function marks the document as printed in Accredo.
• There is more than one way to sign in. Agree the method with whoever looks after your Accredo before you write code.

These basics can take a while to work through before you build anything useful. For a longer look, read Harnessing Accredo's Web Service API.

Using the Rapido SDK

The Rapido SDK is a TypeScript client for the Accredo Web Service API, generated from Accredo's OpenAPI specification. It gives you typed classes for each module, so your editor knows the fields, plus extra helpers for running SQL queries and scripts. It is open source under the Sustainable Use License: free for internal business, non-commercial and personal use. Source and install steps are on GitHub.

Rapido uses the same SDK for the customer integrations we run, so it is used in production every day.

When to have Rapido build it

Writing your own integration makes sense for one internal tool. It costs more when the integration has to stay in step with Accredo every minute of every day, for years. That's the work Rapido already does:

• Integrations with Shopify, WooCommerce, HubSpot and Snowflake, plus pricing and stock file feeds.
• A customer API: plain REST and JSON your own customers can build against, with no OData on their side.
• The Accredo B2B ordering portal for your trade customers.
• Rapido MCP for Accredo, so your team can ask Claude or ChatGPT about live Accredo data and create orders in it.

If you're weighing up building it yourself, get in touch. A 30-minute call is usually enough to tell you which way to go.