A 1 MB CSV test file

About this file

A 1 MB test file in CSV format, sized to exactly 1,048,576 bytes. Free to download with no signup, for verifying upload limits and file-handling behaviour.

The MD5, SHA-1 and SHA-256 values listed above are the real digests of this file. Recomputing them after download confirms the transfer was not corrupted, and they double as known-good expected values when testing a hashing library.

What this size means in practice

1 MB is exactly the nginx client_max_body_size default (1m). Behind a reverse proxy where nobody set that directive, anything larger never reaches your application — nginx answers 413 Request Entity Too Large itself.

That makes it the ideal size for reproducing the classic incident where the app limit was raised to 10 MB yet uploads still fail at 1 MB. If the 413 never appears in your application log, the cause is almost always the proxy layer in front of it.

Getting a feel for this size

On a 10 Mbps link the transfer takes roughly 839 ms, and about 84 ms at 100 Mbps. Base64-encoded it grows to roughly 1,365 KB.

For a typical business CSV of about ten columns and roughly 100 bytes per row, this size corresponds to about 10,486 rows — a useful gauge for whether a spreadsheet can open it or a bulk database import finishes in time. It is a rough estimate; actual counts vary with content and column count.

What to check for this format

CSV is plain text and has no magic bytes of its own. You therefore cannot prove a file is CSV by inspecting a signature; validation has to focus instead on character encoding, delimiters, and quoting rules.

• Whether you process row by row instead of loading every line into memory — the classic cause of out-of-memory failures on large CSVs
• Whether quoted values containing embedded newlines or commas are parsed correctly
• Whether encoding detection is correct — CSVs containing Japanese are a frequent source of mojibake