How to split a CSV file without breaking a row
When you split a CSV file with a general-purpose file splitter, the cut lands at a byte count, often in the middle of a row. The first piece ends on half a record, the next starts on the other half, and neither opens cleanly in a spreadsheet. This app only ever cuts at a line break, so every piece holds complete rows.
It can also copy the first line, usually the column names, to the top of every piece. That turns each part into a usable spreadsheet in its own right rather than a block of anonymous values you have to match back to the original.
The window is small and does one thing. Pick By lines or By parts, type a number, decide about the header, and press Split. The pane shows the file names that are about to be written before you run it.
Split a CSV into multiple files: step by step
- Drop one or more files on the window, or click Choose a file.
- Pick By lines and enter how many lines each part should hold, 1,000 to begin with, or pick By parts and enter how many files you want, from 2 up.
- Tick Repeat the first line at the top of every part for a CSV or TSV with column headings. Leave it off for logs and plain text.
- Press Split. The pieces are written next to the original, which is left alone.
Splitting a large text file, log or subtitle file
The same line-safe cutting works on more than spreadsheets. Server logs that are too big for a text editor to open comfortably, SQL dumps, Markdown notes, line-based JSON, XML and DAT files can all be broken into parts that a normal editor will load. Subtitle files in SRT and VTT format are accepted too.
Line endings are copied byte for byte, so Windows-style files keep their CRLF endings and Unix-style files keep theirs. Nothing is re-encoded on the way through, which also means the parts use whatever character set the original did.
Lines per file or number of parts: which to choose
Choose By lines when something downstream has a limit: an import screen that takes 5,000 contacts at a time, an upload form with a row cap, or a mail-merge tool that slows down on large lists. Every part except the last will have exactly the count you typed.
Choose By parts when you want to share the work out, for example handing a list to four people or running four jobs side by side. The lines are divided as evenly as they will go. With the header option on, the heading line is added on top of each part's share and does not count toward it.
