Open-source TypeScript SDK for ZIMRA fiscalisation. Talk to FDMS directly with your own device certificate, no middleware
Every POS, invoicing and accounting product in Zimbabwe has to fiscalise its receipts with ZIMRA's Fiscalisation Data Management System. The spec is stateful, cryptographic and quiet about failure. Send a signature in the wrong encoding, sort two counters alphabetically or pad the device ID wrong, and FDMS answers with an error code and nothing else. A Red error on one receipt locks the fiscal day, and only ZIMRA can close it.
A shop shouldn't stop trading because a library sorted Card before Cash.
Red error locks the fiscal day until ZIMRA closes it
Offline window before receipts must reach FDMS
Digits the device ID needs in the certificate request, zero-padded
Each POS team was learning FDMS on live devices, one rejected receipt at a time, or paying middleware a fee on every receipt to avoid it. The device's own certificate is all FDMS needs. What was missing was a library that had already made the mistakes on ZIMRA's test environment and shipped the answers as defaults.
“Nobody needs a middleman to fiscalise. They need the hard parts done once, in the open.”
zimra-fdms registers devices, runs mutual TLS, signs hash-chained receipts and opens and closes fiscal days against FDMS. The same package ships a CLI, an MCP server, a local FDMS simulator and a React Native adapter for Android.
Hash-Chained Receipt Signing
Canonical signing strings, cents-exact money and the receipt-to-receipt hash chain, DER-signed the way FDMS verifies them
Registration Without Exporting the Key
The SDK builds the certificate request itself and has your signer sign it, so a key in Android Keystore, an HSM or a cloud KMS can register
One Core, Every Runtime
The fiscal engine uses no Node APIs, so it runs on Node, Bun, Deno, browsers and Hermes. A lint step fails the build if one creeps in
Offline Queue & Crash Recovery
Receipts are signed at sale time and journaled for the 72-hour offline window. A pending marker settles a lost submit without a duplicate
CLI & MCP Server
Register, open the day, submit and close from a terminal, or run the same eight tools from Claude Code over MCP
Simulator & Conformance Vectors
A local FDMS with real mTLS that replays the error codes seen live, plus test vectors that check a port in any language
Fiscalisation, solved once
The hard parts, done in the open
Knowledge that cost real fiscal days
MIT-licensed on npm as zimra-fdms 0.4.1, with docs at zimrasdk.com
Validation errors on ZIMRA's test environment
Automated tests
GitHub stars
Most of the work wasn't code. It was finding out, receipt by receipt, that FDMS wants DER signatures, counters in enum order and a ten-digit device ID. Each of those is now a default with a regression test behind it, and that is what makes the SDK worth installing.
What's Next
Version 1.0: a Gradle build on a real Android device, pipelined offline flush and TLS session resumption.
Carefully selected technologies for performance, scalability, and developer experience.
Core
Core technologies powering the application's foundation and user experience.
Node
AI
Mobile
Testing & Docs
Technologies
Categories
Type Safe
Stack
Next Project
Fetchr
On-demand courier delivery for Harare. Book a rider, track the parcel live, pay when it arrives
View ProjectWork With Me
Let's Build Something Like This
Need an AI-powered product that actually works in the real world? Let's talk about your project.