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TOPCAT vs Tad: catalog facts
TOPCAT	Tad
Free Free to download.	Free Free and open source under the MIT licence.
Windows, macOS, Linux	Windows, macOS, Linux
Handles FITS, VOTable, CDF, CSV and Parquet Interactive exploration of large tables	Opens CSV, Parquet, SQLite and DuckDB data in one app Pivot table view for exploring data without code
Interface and features are oriented toward astronomy Requires Java	Hobby project with known bugs and rough edges Releases are infrequent; the latest is from June 2024
Downloadable app	Downloadable app
Closed source	Open source
License not stated	License: MIT
No account needed	No account needed
Works offline	Works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked September 24, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.