The API for
Dynamics GP.
Read and write Great Plains from your app. One REST + MCP API and a lightweight agent. No Windows middleware, no VPN.
curl api.erpspan.com/v1/customers -H "Authorization: Bearer $LB_TEST_KEY"One secure bridge to Dynamics GP.
Your applications on one side, your on-prem Great Plains server on the other. ERPSpan sits in the middle as a typed, encrypted gateway, with reads and writes flowing both ways.
Three steps. No Windows middleware.
Point your app at ERPSpan and start reading and writing GP. The hard parts are handled for you: the tunnel, eConnect, typing, retries.
Install the agent
A small Windows service runs on your GP server and connects outbound over WSS 443. No firewall changes, no open ports, no VPN.
Call the API
REST or MCP, fully typed. Reads are SELECT-only; writes run through eConnect in a transaction. Same shape for every object.
Get typed data
Customers, vendors, invoices, GL, orders. Read and write, with keyset pagination and idempotent posting built in.
You stay in control.
Your ERP is the crown jewels. ERPSpan is built so a connection can never do more than you’ve allowed.
Read-only by default
Reads run under a dedicated read-only SQL login. Writes are disabled per object until you explicitly whitelist them.
Idempotent writes
Every write takes an Idempotency-Key. Retries and network blips never double-post an invoice or payment.
Full audit trail
Every request is logged: which key, which object, when, and the outcome. Export it or stream it to your own logs.
Credentials stay put
SQL credentials live only on your agent, DPAPI-encrypted. We store hashes of API keys, never the secrets themselves.
20+ GP objects. Read & write.
One consistent, typed interface across the tables and eConnect procedures that matter, so you never touch a DEX_ROW_ID again.
Simple pricing.
No feature gates. Every plan includes all objects, REST + MCP, and idempotent writes.
For a single product connecting to a couple of GP installs.
- Up to 2 connections
- All objects, REST + MCP
- Community support
Embed GP connectivity across all your customers.
- Unlimited connections, no minimum
- Volume pricing from 25 connections
- Priority support & SLAs
For scale, compliance, and dedicated support.
- SSO & SAML
- Dedicated support
- On-prem & self-host
No platform fees. No minimums. Test keys and the Fabrikam sandbox are free forever. You only pay for live connections your app actually calls.
Questions.
Do I have to install anything on Windows?+
One small agent runs as a Windows service on your GP server. It connects outbound only, so you never open a port or expose SQL Server to the internet.
Is it safe to give ERPSpan access to our ERP?+
Reads run under a read-only SQL login, writes are off until you whitelist each object, credentials never leave your server, and every request is audit-logged.
Which Dynamics GP versions are supported?+
GP 2013 through GP 18.x. Reads work anywhere the schema matches; writes use eConnect, which ships with supported GP installs.
Doesn’t GP already have a REST API?+
It does. Service Based Architecture, shipped in 2015. It’s a fine way to call GP from inside your customer’s network: it runs on their IIS server and authenticates Windows domain users. It just doesn’t solve the problem you have. Its object list is still frozen at GP 2015, with no GL journal entries, no sales orders and no purchase orders. It caps at 30 concurrent requests that compete for RAM with your customer’s own GP users, and twenty customers means twenty endpoints and twenty sets of domain credentials. Microsoft agreed GP needed a REST API and shipped one, then stopped. ERPSpan is one endpoint and one key, for every customer, from the cloud.
What about other ERPs like Sage?+
Dynamics GP is first. The same agent-and-API model extends to other on-prem ERPs. Sage 100 is on the roadmap.
Building on Dynamics GP? Let’s talk.
We’re onboarding a handful of design partners, with early access, founder pricing, and direct input into what gets built. If you connect to customers’ GP installs (or you’re about to), we’d love to hear how you handle it today.