Bank Statement Parser

Rust workspace with small tools and a library for working with bank statement formats:

• MT940 (SWIFT Customer Statement Message)
• CAMT.053 (ISO 20022 BankToCustomerStatement)

These are the actual interchange formats used between banks and corporate clients. The library provides typed domain models with parsing and printing for both, plus CLI tools to convert between formats and reconcile transactions across files.

Highlights:

• Hand-written parser for the SWIFT MT940 tag-based text format
• CAMT.053 XML parsing into shared domain types
• Format-agnostic transaction comparison (reconciliation across MT940/CAMT.053 in any combination)
• Library-first design: CLIs are thin wrappers over the reusable parser crate

Stack: Rust · Clap

Repository Structure

• parser — reusable library with domain types and readers/writers for MT940 and CAMT.053
• converter — CLI to convert statements between MT940 and CAMT.053 or pretty‑print them
• comparer — CLI to compare transactions between two statement files (same or different formats)

Requirements

Rust and Cargo installed.

Build

cargo build --workspace

Repository structure

• converter/ — CLI tool (uses the parser crate)
• comparer/ — CLI tool (uses the parser crate)
• parser/ — library crate with:
  • Mt940CustomerStatementMessage — MT940 parsing/printing
  • Camt053Message — CAMT.053 parsing/printing
  • MessageWriter trait — stream output helper
• file_examples/ — sample input files for both formats

Usage — converter

Show help:

cargo run -p converter -- --help

Convert MT940 → CAMT.053 (XML):

cargo run -p converter -- \
  -i file_examples/mt940/mt940.txt \
  -f mt940 \
  -o camt053 > out_camt053.xml

Convert CAMT.053 → MT940:

cargo run -p converter -- \
  -i file_examples/camt053/camt053.xml \
  -f camt053 \
  -o mt940 > out_mt940.txt

Pretty‑print without changing format (omit -o to use Display output):

cargo run -p converter -- -i file_examples/mt940/mt940.txt -f mt940

Usage — comparer

Compare transactions across two files (any combination of formats):

cargo run -p comparer -- \
  --file1 file_examples/mt940/mt940.txt --file1-format mt940 \
  --file2 file_examples/camt053/camt053.xml --file2-format camt053

The tool prints symmetric differences; if none found, it reports "No difference found".

Library usage (parser)

Example: read CAMT.053 and print back to stdout via MessageWriter:

use parser::{Camt053Message, MessageWriter};
use std::fs::File;
use std::io::stdout;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let file = File::open("file_examples/camt053/camt053.xml")?;
    let message = Camt053Message::read_from(file)?;
    let mut out = stdout();
    message.write_to(&mut out)?;
    Ok(())
}

Run tests

cargo test --workspace

Notes

• Sample files are located under file_examples/mt940 and file_examples/camt053.
• All CLIs use Clap, so --help shows the available options and formats.