Compare assembly BOM revisions by part and subassembly
A downloadable browser tool for engineers and purchasing staff comparing two complete assembly spreadsheets. See additions, removals, and changes to descriptions, quantities and units at each part’s assembly path. Save a changes CSV and a JSON record with source rows and comparison settings.
| Assembly path | Result | Old | New | Source row |
|---|---|---|---|---|
| DEMO-ROOT / LEFT | Source quantity per parent | 2 | 3 | 3 |
| DEMO-ROOT / RIGHT / GASKET | Source description | Seal | Seal revised label | 6 |
| DEMO-ROOT / LEFT / GASKET | Derived quantity per root | 4 | 6 | 4 |
Keep repeated parts in their assembly branches
Part identity includes every parent part ID. A gasket used in both the left and right subassemblies is compared separately in each branch. Quantity changes entered in a source row are separate from quantity impacts calculated from a changed parent.
In the included example, LEFT changes from two to three subassemblies. Each still contains two GASKET parts, so its gasket quantity per root changes from four to six. RIGHT/GASKET keeps quantity one and has a description change. The report shows two source changes and one derived quantity impact.
Follow the example with the old CSV, new CSV, expected changes CSV and JSON report.
Check your export before buying
Both files must describe the same complete assembly and scope. Each selected table needs five separate columns:
- Integer level, starting with one root at level 0.
- Part ID stored as text, including assembly IDs.
- Description stored as text.
- Positive decimal quantity per immediate parent, with root quantity 1.
- Unit stored as text. Assemblies with children must use EA.
Rows must follow their parents. Use UTF-8 CSV or TSV, or an XLSX worksheet, up to 10 MiB per file and 10,000 data rows. Select the worksheet, header and columns yourself; suggested mappings need checking. Choose whether to keep or trim surrounding whitespace.
This format is narrower than a CAD or PLM comparison system. It does not join worksheets or infer missing hierarchy. Flat PCB exports, CAD cut lists, partial updates, already multiplied quantities, duplicate part IDs under the same parent, and unit conversion are outside its scope. A moved part appears as a removal and an addition. XLS and XLSM files are unsupported. Formulas and merged cells in mapped data columns are refused. Worksheets with hidden rows or active filters are refused.
Open locally and save your report
- Extract the ZIP and open its HTML file in a desktop browser.
- Select both files, map the columns and inspect the source-row previews.
- Confirm complete snapshots and quantities per parent, then compare and download CSV and JSON.
The download contains the HTML tool, instructions and two demonstration CSVs. No server or software installation is needed. The tool makes no network requests and uses no browser storage. Files stay in the current tab; closing or reloading clears them. Downloaded reports contain your selected component data.
This version has been checked on Linux Chromium. Operation on Windows or macOS, including Chrome and Edge, has not yet been verified.
Use the report as a read-only comparison aid and verify it against source records before acting. It does not approve designs, substitutions, purchasing or manufacturing. Do not use it for safety-critical or regulated BOMs. Include component data only, without personal or customer records.
Download and support
A$29 once, tax included. No subscription. Use the purchased version indefinitely within your organisation; no redistribution of the tool or promise of future updates. Read the licence.
Pay through Stripe and download the ZIP from the confirmation page. Terms and refunds apply. Website and checkout data are covered by our privacy policy; the downloaded tool processes your BOMs locally.
Built and maintained by AI agents at Madrasco. For support, contact [email protected]. Replies may be AI-assisted; a human owner can be reached on request.