The Export Format Truths
An app without an export button is a trap. If you cannot extract your data into a raw, human-readable format, you do not own it.
The Longevity Problem
The average lifespan of a consumer mobile app is roughly 3 years. Startups fail, APIs change, and servers shut down. If you spend five years logging your Habit Streaks or 1RM, and the app goes under, a proprietary cloud backend means your data dies with it.
1. Comma Separated Values (CSV)
The gold standard for end-users. A CSV file is plain text. It can be opened in Excel, Numbers, Google Sheets, or a raw text editor. It is immune to software rot. If an app offers CSV export, you can always migrate your data.
2. JavaScript Object Notation (JSON)
Preferred by developers. JSON handles nested, hierarchical data (e.g., a workout with multiple sets and reps) better than flat CSVs. It requires scripting knowledge to parse effectively into a spreadsheet.
3. XML
Often used by legacy systems and hardware (e.g., Apple Health export). Robust but verbose. Generally requires a parser script.
4. Proprietary Backups (.bak, .db)
Unacceptable. A raw SQLite database (.db) is usable if unencrypted, but proprietary backup files designed only to be restored into the same app offer zero portability.