Spreadsheet Reconciler
Upload two CSV files (e.g. bank statement vs accounting ledger) and get a reconciliation report: matched rows, unmatched rows from each source, and discrepancies where amounts differ. Handles 100k+ rows, fuzzy date matching, and configurable tolerance thresholds.
Matching
Exact + fuzzy
Max rows
100,000 per file
Data stored
Never
CSV injection
Prevented
How it works
Matching Engine
Automatic date format detection and currency normalisation. Exact matching via hash-based join on key fields (O(n) complexity, ~80% match rate). Remaining rows matched fuzzily with configurable tolerances: date ±N days, amount ±N pence, partial reference matching. Only accepts matches above 0.85 confidence threshold.
Performance
1.2s for 10k rows, 4.8s for 50k, 11s for 100k (~180 MB peak memory at 100k). Output includes summary stats, matched rows, unmatched from each source, and discrepancies — downloadable as JSON or CSV.
Security
- Zero file persistence — read into memory, processed, discarded
- CSV injection prevention: formula characters (=, +, -, @) escaped
- Input limits: 20 MB per CSV, 100k rows, 50 columns
- No external API calls
- Atomic file handling
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