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Parse raw SWIFT MT messages into clean, human-readable JSON.

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swift-message-parser

Parse raw SWIFT MT messages into clean, human-readable JSON. Runs entirely in your browser. No install, no server, no dependencies.

What It Does

Paste a raw SWIFT MT103 or MT202 message into the tool, and get back:

  • Structured JSON: every field tag decoded and labelled
  • Human-readable field names: :32A: becomes Value Date / Currency / Amount
  • Field-level validation: missing mandatory fields, invalid formats, unknown tags
  • Envelope decoding: sender BIC, receiver BIC, message direction from header blocks

Supported Message Types

Type Name Status
MT103 Single Customer Credit Transfer ✓ v1.0
MT202 General Financial Institution Transfer ✓ v1.0
MT300 FX Confirmation ✓ v1.0
MT940 Customer Statement Message ✓ v1.0
MT950 Statement Message ✓ v1.0
MT199 Free Format Message ✓ v1.0
MT202 COV Cover Payment Planned v1.1
MT900 Confirmation of Debit Planned v1.1
MT910 Confirmation of Credit Planned v1.1

Quick Start

No install required.

git clone https://github.com/shanx/swift-message-parser
cd swift-message-parser
open index.html

Or just open index.html directly in any modern browser.

Paste a raw MT message. Click Parse. Done.

Example

Input: raw MT103

{1:F01NWBKGB2LAXXX0000000000}
{2:I103COBADEFFXXXXN}
{4:
:20:SHANX-20250101-001
:23B:CRED
:32A:250101USD10000,00
:50K:/GB29NWBK60161331926819
Acme Corporation
1 Canada Square
London E14 5AB
:59:/DE89370400440532013000
Global Trade Bank
Neue Mainzer Str 32
Frankfurt 60311
:70:INVOICE REF 2025-INV-0042
:71A:SHA
-}

Output: structured JSON

{
  "messageType": "MT103",
  "transactionReference": "SHANX-20250101-001",
  "bankOperationCode": "CRED",
  "valueDate": "2025-01-01",
  "currency": "USD",
  "amount": 10000.00,
  "orderingCustomer": {
    "account": "GB29NWBK60161331926819",
    "name": "Acme Corporation",
    "address": ["1 Canada Square", "London E14 5AB"]
  },
  "beneficiary": {
    "account": "DE89370400440532013000",
    "name": "Global Trade Bank",
    "address": ["Neue Mainzer Str 32", "Frankfurt 60311"]
  },
  "remittanceInformation": "INVOICE REF 2025-INV-0042",
  "chargeBearer": "SHA",
  "_meta": {
    "valid": true,
    "errors": [],
    "warnings": [],
    "parsedAt": "2025-01-01T09:00:00Z"
  }
}

Tech Stack

Layer Choice Reason
UI Vanilla HTML + CSS Zero dependencies, open and run
Logic Vanilla JavaScript (ES6+) Runs in browser, no compile step
Text parsing Native JS string + regex MT format is plain text, no library needed
Syntax highlighting highlight.js (CDN) JSON output colouring
CSS framework UIKit 3 (CDN) Navbar, dropdowns, modals
Fonts IBM Plex Mono + Sans Trading-terminal aesthetic

One HTML file. No npm. No build step. No server.

Architecture

swift-parser/
├── index.html              # Entry point: navbar, split panels, modals
├── assets/
│   ├── style.css           # Design system (CSS custom properties)
│   ├── app.js              # Parser engine, schemas, samples, UI logic
│   └── *.svg               # Icon assets
├── samples/
│   ├── mt103-sample.txt    # Reference MT103 sample
│   └── mt202-sample.txt    # Reference MT202 sample
└── README.md

How the Parser Works

SWIFT MT messages are plain text with a consistent structure: each field starts with a :TAG: identifier on a new line, followed by its value. The parser:

  1. Extracts envelope blocks: parses {1:...} basic header and {2:...} application header for sender/receiver BIC and message type
  2. Isolates the text block: extracts {4:...-} containing the actual message fields
  3. Splits on field tags: regex splits on :XX: or :XXX: patterns, handling multi-line values
  4. Maps tags to definitions: each tag is looked up in a shared field dictionary with human-readable names
  5. Decodes compound fields: :32A: encodes date + currency + amount in one value. These are decoded into separate fields
  6. Validates mandatory fields: each message type has required tags. Missing ones surface as errors

Field Tag Reference

Tag Name Format Notes
:20: Transaction Reference 16x Mandatory. Unique reference assigned by sender
:21: Related Reference 16x Reference to a related message
:23B: Bank Operation Code 4!a Mandatory. Usually CRED for credit transfers
:32A: Value Date / Currency / Amount 6!n3!a15d Mandatory. Date in YYMMDD, ISO 4217 currency, decimal amount
:50K: Ordering Customer 4*35x Account + name + address of sending party
:52A: Ordering Institution BIC Sender's bank BIC
:57A: Account With Institution BIC Beneficiary's bank BIC
:59: Beneficiary Customer 4*35x Account + name + address of receiving party
:70: Remittance Information 4*35x Payment reference / invoice details
:71A: Details of Charges 3!a SHA shared / OUR sender pays / BEN beneficiary pays
:72: Sender to Receiver Information 6*35x Optional free-text instructions

Features Roadmap

v1.0: Launch

  • MT103 full field parsing and decoding
  • MT202 full field parsing and decoding
  • MT300 FX Confirmation parsing and decoding
  • MT940 Customer Statement parsing
  • MT950 Statement Message parsing
  • MT199 Free Format parsing
  • Mandatory field validation
  • Envelope block parsing ({1:...} {2:...} headers)
  • Compound field decoding (:32A: date/currency/amount split)
  • Custom MT syntax highlighting
  • Load sample message button
  • Copy JSON to clipboard
  • Dark-mode-ready design system

v1.1: Coverage

  • MT202 COV (cover payments)
  • MT900 / MT910 debit/credit confirmations
  • IBAN format validation
  • BIC/SWIFT code format validation
  • Plain English summary panel
  • PDF export

v1.2: Extended

  • Batch parse: paste multiple messages separated by $

Future / Vision

This tool deliberately stays as a single HTML file with vanilla JavaScript. Browsers run JS, not TypeScript, and a build/compile step would break the "open and use" simplicity that makes it genuinely useful.

Phase 1: Browser tool (this repo, v1.x) Single HTML file. Paste and parse. No install.

Phase 2: TypeScript library The parsing logic extracted into a typed npm package with proper interfaces for each message type.

Phase 3: REST API A Fastify + TypeScript wrapper around the library for server-side parsing.

Phase 4: Integration with RegWatch MT103/MT202 parsing becomes one module in the broader regulatory intelligence stack.

MT Message Format Reference

SWIFT MT messages are organised into categories by the first digit of the message type number.

Category 1: Customer Payments & Cheques
Type Name Priority
MT101 Request for Transfer Medium
MT103 Single Customer Credit Transfer ✅ v1.0
MT103 STP Straight Through Processing variant v1.1
MT103 REMIT Extended remittance info variant v1.1
MT104 Direct Debit & Request for Debit Transfer Low
MT107 General Direct Debit Message Low
MT110 Advice of Cheque Low
MT111 Request for Stop Payment of Cheque Low
MT112 Status of a Request for Stop Payment Low
Category 2: Financial Institution Transfers
Type Name Priority
MT200 Financial Institution Transfer for Own Account Medium
MT201 Multiple FI Transfer for Own Account Low
MT202 General Financial Institution Transfer ✅ v1.0
MT202 COV Cover Payment v1.1
MT203 Multiple General FI Transfer Low
MT204 Financial Markets Direct Debit Low
MT205 Financial Institution Transfer Execution Medium
MT210 Notice to Receive Medium
Category 3: Treasury & Derivatives
Type Name Priority
MT300 FX Confirmation High
MT304 Advice/Instruction of FX Deal Medium
MT305 FX Option Confirmation Medium
MT320 Fixed Loan/Deposit Confirmation Medium
MT330 Call/Notice Loan/Deposit Confirmation Low
MT340 Forward Rate Agreement Confirmation Low
MT360 Single Currency Interest Rate Swap Low
MT361 Cross Currency Interest Rate Swap Low
Category 4: Collections & Cash Letters
Type Name Priority
MT400 Advice of Payment Low
MT410 Acknowledgement Low
MT412 Advice of Acceptance Low
MT430 Amendment of Instructions Low
MT450 Cash Letter Credit Advice Low
MT456 Advice of Dishonour Low
Category 5: Securities
Type Name Priority
MT500–599 Securities messages (confirmations, instructions, statements) Low for v1
Category 6: Precious Metals & Syndications
Type Name Priority
MT600–699 Precious metals, syndicated loans Very low
Category 7: Documentary Credits & Guarantees
Type Name Priority
MT700 Issue of Documentary Credit (Letter of Credit) Medium
MT707 Amendment to Documentary Credit Medium
MT710 Advice of Third Bank's Documentary Credit Low
MT740 Authorisation to Reimburse Low
MT742 Reimbursement Claim Low
MT760 Guarantee / Standby Letter of Credit Medium
MT767 Guarantee Amendment Low
Category 9: Cash Management & Customer Status
Type Name Priority
MT900 Confirmation of Debit High
MT910 Confirmation of Credit High
MT920 Request Message Medium
MT940 Customer Statement Message High
MT941 Balance Report Medium
MT942 Interim Transaction Report Medium
MT950 Statement Message (FI to FI) High
MT970 Netting Statement Low
Common Group Messages
Type Name Priority
MT190/191 Charges / Request for Payment Low
MT192/195/196 Cancellation / Queries / Answers Medium
MT199 Free Format Medium
MT292/295/296 Same as above for Cat 2 Low
MT999 Free Format (general) Medium

Tags

swift mt103 mt202 payments fintech banking correspondent-banking message-parser open-banking iso15022

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Parse raw SWIFT MT messages into clean, human-readable JSON.

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