Free GEDCOM Analyzer: Inspect, Validate and Visualise Your Family Tree Online

A GEDCOM analyzer reads the standardised text-based genealogy format that most family-history software exports (.ged or .gedcom) and turns it into structured data you can query and visualise. A good analyzer goes well beyond a tree viewer — it cross-references every individual, family, fact, source and place in the file to surface patterns and problems that are impossible to spot manually in a tree of any size.

GEDminer parses your file in three passes: a fast structural pass to read the GEDCOM grammar (level numbers, tags, cross-references — supporting both GEDCOM 5.5 / 5.5.1 and the newer GEDCOM 7 spec), a normalisation pass that tries multiple character encodings (UTF-8, Windows-1252, Mac Roman, Latin-1, ANSEL) so old files with mangled accents render correctly, and a semantic pass that builds an in-memory model of individuals, families, events, sources and citations.

From that model, every report — duplicates, errors, location standardisation, migration, census gaps, occupations, surnames, lifespans — is computed on demand in a background worker so the UI stays responsive even on trees with hundreds of thousands of people.

Sharing a family tree with a cousin, uploading it to a collaborative site, or publishing a one-name study all expose your data to scrutiny. Errors that were invisible while you were the only reader become very visible the moment anyone else looks. Running the tree through an analyzer first catches the things you can't unsee:

• Impossible vital dates (deaths before births, marriages at age 4, ages over 120)
• Duplicate individuals that arrived from a merged GEDCOM and were never reconciled
• Encoding corruption that turns "Müller" into "Müller" and "O'Brien" into garbled bytes
• Unsourced facts that look authoritative but have no underlying citation
• Disconnected branches that you forgot were even in the file
• Place inconsistencies that defeat downstream search and mapping

Spending half an hour with the analyzer before publishing or sharing typically eliminates 80% of the issues a careful reader would otherwise spot — and it lifts your data quality score in the process.

Every analysis ends with a single weighted score from 0 to 100, broken into three components:

1. Completeness (40%) — what fraction of expected facts (birth, death, parents, marriage, place) are actually present.
2. Sourcing (30%) — total source citations divided by total facts, expressed as a percentage. A well-sourced tree typically lands above 60%.
3. Consistency (30%) — how few logical errors (impossible dates, broken links, encoding issues) the integrity scanner finds, normalised by tree size.

The score is comparable across exports, which means you can re-export after a cleanup pass and immediately see whether your work moved the needle. There's also an optional community percentile so you can see where your tree sits relative to others of similar size.

Genealogy data is sensitive. It contains living relatives, addresses, and sometimes adoption or paternity events that family members would not want exposed. GEDminer's analyzer is engineered around this reality.

The .ged file is opened with the browser's File API, parsed in a Web Worker, held in memory while you use the app, and discarded when the tab closes. If you create an optional account and choose to save an analysis, GEDminer stores a compressed version of the parsed analysis data so you can reopen it later. This may include names, dates, places and family relationships extracted from your GEDCOM. Your original .ged file is still never uploaded or stored.

Performance is just as important. The streaming parser uses incremental \indexOf\ scans rather than loading the whole file into a string at once, so files up to 500MB and trees over 200,000 individuals stay responsive. The UI virtualises long lists, debounces search, and offloads heavy work (duplicate scoring, geocoding, kinship calculation) to background workers.

Desktop genealogy programs are designed for data entry and tree editing. GEDminer is designed for data analysis and quality control. They complement each other rather than compete.

A typical workflow: do your day-to-day editing in your existing program, then once a month export a GEDCOM and run it through GEDminer. The analyzer gives you the prioritised cleanup list (duplicates, impossible dates, missing sources, incomplete families); you make the fixes back in your editor and re-export.

The analyzer is intentionally read-only — it never writes back to your file. This keeps the workflow safe, and it keeps GEDminer compatible with every desktop and online genealogy program that can export standard GEDCOM 5.5 / 5.5.1 / 7.