Now in open beta — free for terminal developers

Test every payment scenario.
Ship with confidence.

SimuPay is a multi-protocol acquirer host simulator with a real-time web dashboard. Connect any payment terminal or our Android demo app and run any flow — approvals, declines, timeouts, partials — without touching a live bank. APACS 70, Amex and ISO 8583 all supported.

Integration guide
simupay.co.uk — Live Dashboard
247
Total
189
Approved
41
Declined
12
Timeouts
5
Partial
APPROVED 12345678 •••• 4111 £24.99 just now
DECLINED 12345678 •••• 5500 £150.00 12s ago
APPROVED 87654321 •••• 3782 £8.50 28s ago
TIMEOUT 87654321 •••• 6011 £67.00 45s ago
PARTIAL 12345678 •••• 4012 £99.99 1m ago
Features

Everything you need to test
a UK payment terminal

No mocking libraries. No brittle stubs. A real TCP server that speaks your terminal's protocol.

Real-time transaction feed
Watch every authorisation, financial presentation, and reconciliation flow through your terminal in real time — streamed to the browser over WebSocket the moment it arrives.
Scenario builder
Chain outcomes in any order — approve, decline, timeout, partial, fraud, reversal. Scenarios loop automatically or stop after the last step, and can be shared via QR code or URL.
Amount-based rules engine
Control responses by last digit: amounts ending in 0 approve, 1 decline, 7 timeout, and so on. Test all edge cases with a single set of card transactions, no scenario setup required.
Multi-protocol support
Simultaneous APACS 70, Amex Standard 70, and ISO 8583 servers on separate ports. MAC computation, EMV data parsing, and TID-based routing all included.
TLS on every connection
All TCP connections are TLS-secured out of the box. Auto-generates a self-signed RSA-2048 certificate on startup, or bring your own. Retail MAC (ANSI X9.19) is computed and verified.
Share & compare transactions
Generate a shareable link for any transaction — or select two and do a byte-level, EMV-tag side-by-side comparison. Share links work without an account, perfect for reporting bugs to integrators.
Reports & analytics
Build custom dashboards with KPI cards, gauges, line charts, bar charts, donuts and data tables. Group by time or terminal, create reusable templates, and track trends across any report field.
Android logging & reporting
Drop-in Android log replacement streams log entries, screenshots and images to the dashboard in real time. A built-in report client sends transaction data for analytics. Filter by TID, share sessions with image slideshows.
Multi-user with roles
Team members each have their own account, TID list, and transaction history. An admin portal provides user management, subscription tracking, email integration, and platform-wide activity charts.
Android demo app
A ready-made Java payment app with NFC contactless support. Connects via APACS or ISO 8583, sends logs, screenshots and transaction reports to the platform automatically. Ideal for demoing the full system.
Getting started

Up and running in minutes

No SDKs to install on the terminal. No bank account. Just point and shoot.

1
Create your account
Sign up in seconds. Register a terminal ID (TID) that matches the one programmed into your physical terminal.
2
Point your terminal
Set the acquirer host IP and port on your terminal to SimuPay's TCP address. TLS is always on — disable cert validation in test mode or install the auto-generated CA cert.
3
Run your scenarios
Tap a card on your terminal. Watch the transaction appear in the dashboard instantly. Use the built-in rules engine or build a custom scenario to control every response.
Protocol support

Multiple protocols, one simulator

Full transaction lifecycle from authorisation through to reconciliation — across APACS 70, Amex, and two ISO 8583 implementations.

Protocol / Message type Msg code Framing MAC EMV Response codes
APACS 70 — Authorisationauth
Pre-auth and combined auth/sale
 12 / 18 STX/ETX + 2-byte len — ✓ 00 05 / 51 / 59
APACS 70 — Financial Presentationsale
Debit, credit, contactless, and chip
 11 / 13 STX/ETX + 2-byte len ✓ ✓ 00 / 10 04 / 05 / 09 / 96
APACS 70 — FP Refund / Creditrefund
Merchant-initiated credit back
 40 / 41 STX/ETX + 2-byte len ✓ ✓ 00 05 / 96
APACS 70 — Reconciliationrecon
End-of-day session totals
 62 STX/ETX + 2-byte len ✓ — 95
Amex Standard 70amex
American Express variant framing
 11 / 12 / 41 STX/ETX (no length) — ✓ 00 05 / 51
ISO 8583 — Variant Aiso-a
Sale, auth, reversal, reconciliation, network management
 1200 / 1220 / 1420 / 1500 / 1804 STX/ETX + 2-byte len — ✓ 000 100 / 400 / 500
ISO 8583 — Variant Biso-b
Auth, sale, reversal, network management
 0100 / 0200 / 0400 / 0800 4-byte ASCII length — ✓ 00 05 / 12 / 51
Retail MAC (ANSI X9.19) computed on all FP and reconciliation responses. Key rotation follows the standard acquirer terminal specification.
BER-TLV EMV tag parsing — all ICC data in the transaction is decoded and shown tag-by-tag in the dashboard and comparison view.
Scenario builder

Build repeatable test scripts in seconds

  • Chain any sequence of outcomes: approve → approve → decline → timeout
  • Set a fallback outcome for when the scenario sequence is exhausted
  • Loop mode restarts from step 1 automatically for long-running load tests
  • Share any scenario as a URL or QR code — scan on a mobile to activate instantly
  • Override partial-approval amounts, reversal responses, and system error codes
Scenario — Certification Run
1. APPROVE Standard approval RC 00
2. APPROVE Signature required RC 00
3. DECLINE Do not honour RC 05
4. PARTIAL Partial approval RC 10
5. TIMEOUT Connection closed (no response)
After step 5 → loop back to step 1 ACTIVE
Who it's for

Built for everyone who touches payment terminals

💳
Terminal developers
Iterate on your terminal integration without needing a bank test environment. Verify message structure, MAC calculation, and EMV data handling locally.
🔬
QA & test engineers
Reproduce every edge case — partial approvals, reversals, network timeouts — reliably and on demand. Run the same scenario hundreds of times without manual intervention.
📋
Certification teams
Build the exact outcome sequence your acquirer certification script requires. Loop through all required response codes in one session and share the transaction log as evidence.
🏗️
Fintech integrators
Integrate a payment terminal into your application without access to a live acquirer. Develop and test your business logic against real wire-format messages.
Free during open beta

Ready to stop guessing
and start testing?

Create an account, register your terminal ID, and send your first transaction in under five minutes. No credit card, no contracts.

Read the docs

Questions? Need a feature? See the integration guide or reach out to the team.

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