CSV Doctor (free)

30-second health check for any spreadsheet: encoding, mixed date formats, junk in numeric columns.

Finds the bug where one '-' turns a revenue column into text and totals go wrong
Counts each date format separately, so mixed 2026年4月8日 / 03/12/2026 columns are exposed
Prints the exact pd.read_csv call that loads your file correctly
Exit code 1 on HIGH issues — drop it in cron or CI
Free, no email required. If it saves you an hour, the paid tools will save you ten.

No account, no email required. Download starts immediately.

What you get

A single Python file plus a one-page README — no framework, no account, no license server.
Sample data and a runnable demo, so you can see the output before you read the code.
Source included. Runs offline on Python 3.9+. Most tools use the standard library only.

unzip csv-doctor.zip && cd csv-doctor
pip install -r requirements.txt   # only if the README lists one
python csv-doctor.py demo/input.csv -o out.csv

One-time payment, no subscription, no seat count. If the file will not run on your machine, reply to the order and it gets fixed or refunded.