What is INI?

INI is the oldest configuration format still in daily use: named sections, then key equals value lines.

Who uses it

Windows software, PHP, Git and a long tail of tools that never moved on.

Writing INI

Each row becomes a section named after its first column, with one key per remaining column.

What it can hold

INI is a data interchange format. INI holds key-value pairs under sections, so a table has to become one section per row. A machine can read it back, but only by following the conventions rather than a rule the format enforces.

It cannot express

Types. Every value is text. A column of digits is indistinguishable from a column of numbers until something downstream decides to read it as one, which is where a leading zero usually disappears.
A null. An absent value and an empty one look the same, and nothing in the file says which was meant.
A line break inside a cell. One would end the row, so it has to be replaced before writing.
Any formatting. Bold, colour, column widths and merged cells have nowhere to go.
A header row. Column names are repeated on every record instead, which is why a file in this format is larger than the table it holds.

What it looks like

Example INI

[007]
id=007
name=Halima Yusuf
role=Analyst, data
started=2024-03-15
hours=38.5

[012]
id=012
name=Jonah "Jo" Pryce
role=Engineer
started=2025-11-02
hours=

[104]
id=104
name=Wei Chen
role=Manager
started=2023-06-30
hours=40

Questions

How do I open INI files?

INI is written by Tablizer rather than read by it. Open the file in whichever tool the format belongs to.

Is INI a good format for sharing data?

It depends who is receiving it. Windows software, PHP, Git and a long tail of tools that never moved on. If the recipient is outside that group, a plain CSV travels further than anything else.