CSV, JSON, and Excel all store tabular data, yet picking the wrong one for the job creates real pain: leading zeros vanish, accented characters turn to mojibake, nested fields get flattened into gibberish, and a 40 MB spreadsheet chokes the API that was expecting a lean JSON array. The difference between the three formats isn't quality — it's audience. CSV is for machines that import, JSON is for code that consumes, and Excel is for humans who read.

This guide breaks down when each format wins, the pitfalls that bite during conversion, and the fastest free way to move between all three. Every converter linked below runs in your browser with no sign-up and no file limits games — up to 50 MB per file, processed locally, so your customer data never sits on a stranger's server.