A local, offline desktop app that builds and exports your bank's bulk-payment import files — replacing the clunky Excel process.
Santander, HSBC, Barclays, Lloyds, NatWest & more — via Bacs Standard 18, ISO 20022 (UK) and SEPA (EUR).
🌐 Website · ⬇️ Download · Changelog · Roadmap · Bank formats
Enter payments (or import/paste from Excel), fix any problems with inline validation (including a real UK modulus check), and export the exact file your bank expects — Bacs, ISO 20022 or SEPA. Everything runs on your own machine — no data ever leaves your computer, and what's stored is encrypted.
| Choose your bank — guided wizard | Build batch |
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| Home — dark mode | Build batch — dark mode |
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- ✅ Multiple banks & formats — Santander (Bacs import + mixed payments), plus the cross-bank standards Bacs Standard 18, ISO 20022 (UK domestic GBP) and SEPA (euro/IBAN). Pick your bank and the right format is offered. (Verify with a test upload — formats are built from public specs.)
- ✅ Guided wizard — a step-by-step start (Choose your bank → Start your batch → Build & export) with a searchable bank/format list that separates banks from cross-bank formats and shows each option's supported formats.
- ✅ Light & dark themes — System / Light / Dark, remembered between launches.
- ✅ UK modulus check — the official VocaLink check flags sort code/account combinations that can't be real accounts (likely typos), as an amber warning.
- ✅ Inline, per-field validation — bad cells are highlighted with the reason; the Export button stays disabled until everything is clean.
- ✅ Editable grid + paste from Excel — type straight into the table, paste rows from a spreadsheet, use the quick-add form, or import a CSV (columns auto-detected).
- ✅ Saved payees & batch history — reuse beneficiaries and reload past runs.
- ✅ Encrypted local storage — payees, batches and settings are encrypted with your
OS keychain (
safeStorage). Fully offline. - ✅ Auto-opens the generated file so you can eyeball it before uploading.
Grab the latest installer for your OS from the Releases page:
| OS | File |
|---|---|
| macOS | PayBatch-x.y.z.dmg |
| Windows | PayBatch-Setup-x.y.z.exe |
| Linux | PayBatch-x.y.z.AppImage / .deb |
macOS — the app is signed with an Apple Developer ID and notarized by Apple, so it opens with a normal double-click (no Terminal step needed).
Windows — the installer isn't code-signed yet, so SmartScreen may appear; click More info → Run anyway.
git clone https://github.com/victorsaly/batch-payment-app.git
cd batch-payment-app
npm install
npm start # Vite dev server + Electron, with hot reloadRequires Node.js 18+. The UI is React + Vite; the payment-format engines are pure,
dependency-free modules reused by the renderer via src/renderer-src/core.js.
npm run dist:mac # macOS .dmg + .zip
npm run dist:win # Windows NSIS installer
npm run dist:linux # Linux AppImage + .debOutput lands in dist/.
Pushing a version tag triggers .github/workflows/release.yml,
which builds on macOS, Windows and Linux runners and uploads the installers to a
GitHub Release (created as a draft for you to review and publish):
# bump "version" in package.json first, then:
git tag v1.0.0
git push origin v1.0.0No secrets to configure — it uses the built-in GITHUB_TOKEN.
Pick your bank, then the Output format offered for it. PayBatch can generate:
- Santander Connect — Bacs payment import + mixed payments (below)
- Bacs Standard 18 — the cross-bank fixed-width credit file
- ISO 20022 —
pain.001.001.09UK domestic GBP (sort code + account) - SEPA —
pain.001.001.03euro credit transfers (IBAN/BIC, BIC optional)
The full bank-by-bank matrix is in FORMATS.md. The Santander formats:
Comma-separated .txt, three record types:
PAYMENT,HEADER,<creationDate ddmmyyyy>,<fileLocationId>,<sequenceNo>
PAYMENT,<BACS|MULTIBACS>,<debit 6n+8n>,<name 35>,<sort 6n>,<account 8n>,<amount>,<paymentDate ddmmyyyy>,<reference 18>,<rti>
PAYMENT,TRAILER,<hashTotal 15n in pence>,<recordCount>
BACS = single payments; MULTIBACS = multiple payments sharing one debit account
and date (reference becomes mandatory). Free-text fields are uppercased and limited to
A–Z 0–9 . - / & space; the hash total is the value in pence, zero-padded to 15.
Headerless, one row per payment, LF line endings, mixed-case preserved. Reverse-engineered byte-for-byte from a real sample. Only a payment date and the beneficiary rows are needed.
⚠️ The mixed format has no published spec — it's matched against a sample. Always do one small test upload in Santander Connect before relying on either format.
The complete layout for both formats lives in one file:
src/santander.js (SPEC and MIXED blocks).
| Field | Rule |
|---|---|
| Beneficiary name | Required. Bacs: uppercased, max 35 (first 18 reach Bacs). Allowed: A–Z 0–9 . - / & space. |
| Sort code | Exactly 6 digits (dashes/spaces ignored). |
| Account number | Exactly 8 digits. |
| Amount | Greater than 0, pounds & pence (e.g. 150.50). |
| Reference | Max 18 chars. Mandatory for MULTIBACS; optional otherwise. |
| RTI reference | Bacs only, optional. Starts with /, e.g. /123. |
- All data is stored only on your computer, encrypted via the OS keychain
(Keychain on macOS, DPAPI on Windows) using Electron
safeStorage. - The app makes no network requests (enforced with a strict Content-Security-Policy).
- An older plaintext data file is migrated to the encrypted store on launch.
- The renderer has no Node/filesystem access — it talks to disk only through a small,
explicit IPC bridge (
preload.js).
| File | Purpose |
|---|---|
main.js |
Electron main process — window, encrypted storage, import/export dialogs |
preload.js |
Secure IPC bridge between UI and filesystem |
src/santander.js · standard18.js · iso20022.js · sepa.js · modulus.js |
Pure format engines + validation |
src/banks.js |
Bank / cross-bank-format registry |
src/renderer-src/ |
React + Vite UI (screens, components, store); reuses the engines via core.js |
src/styles.css |
Design-token stylesheet (light + dark) |
test/run.js |
Dependency-free test suite (npm test) |
.github/workflows/ |
CI + release pipelines |
npm testCovers byte-exact reproduction of both formats, validation rules, and CSV import.
This is an independent tool, not affiliated with, endorsed by, or supported by Santander. Provided "as is" without warranty (see LICENSE). You are responsible for verifying every payment detail and reconciling totals before submitting a file to your bank.
MIT © 2026 Victor Saly