TOML to CSV Converter

Convert a TOML array-of-tables into a spreadsheet

TOML is a config format, so its repeated [[section]] blocks are really a table in disguise: every [[users]] entry is a record and every key inside it is a field. This tool turns that structure into CSV — one row per entry, one column per key — so you can open a Cargo.toml, a pyproject.toml, a Netlify or Hugo config, or any hand-written TOML data file in a spreadsheet, load it into a database, or diff it against another export.

The header is the union of every key seen across all entries, not just the keys of the first one. Config files are routinely ragged — one server has a region, the next doesn't — and taking the first entry as the schema would silently drop the rest. Missing values become empty cells instead.

Everything runs in your browser through WebAssembly. The TOML you paste is never uploaded.

Worked example

Input:

[[users]]
name = "Ada"
role = "admin"
tags = ["founder", "ops"]

[[users]]
name = "Linus"
role = "dev"

With the defaults (auto-detect table, flatten nested tables, arrays as JSON, union header, comma delimiter, header row on):

name,role,tags
Ada,admin,"[""founder"",""ops""]"
Linus,dev,

Switch Array values to Indexed columns and the same input becomes name,role,tags.1,tags.2 with founder and ops in their own cells — ready to sort and filter.

Nested tables

A sub-table inside an entry has no natural cell to live in, so you choose:

[[servers]]
name = "web-1"
addr = { city = "Berlin", zip = "10115" }

• Flatten to dot-notation columns (default) → columns name, addr.city, addr.zip. Best for spreadsheets, because every leaf is filterable.
• Keep as JSON in one cell → columns name, addr, with {"city":"Berlin","zip":"10115"} in the cell. Best when a downstream tool re-parses the value.
• Skip nested tables → column name only. Best when the nesting is metadata you don't want in the export.

Flattening recurses, so [servers.addr.geo] becomes addr.geo.lat.

Controls and limits

• Array-of-tables path: leave blank to auto-detect — the first root-level array-of-tables wins, then nested ones. Give a dotted path like servers.pool to pick a specific one when a document has several. Quoted TOML keys (["odd key"]) can't be addressed this way.
• Header columns: union keeps first-seen document order, sorted is alphabetical (stable across files with different key orders), first locks the schema to the first entry and drops later extras.
• Array values: json, join (a; b in one cell), or columns (1-based tags.1, tags.2 — the column count is driven by the longest array in the document).
• CSV delimiter: comma, semicolon, tab, or pipe. Output is RFC 4180 quoted, so a value containing the delimiter, a ", or a newline is quoted and escaped correctly.
• Include header row: turn off to append rows to a sheet that already has headers.
• Capped at 20,000 rows and 2,000 columns per run. For larger files, use the CLI command shown above in a local pipeline.
• Comments are not preserved. TOML parsers discard them, so # note lines never reach the CSV.
• A document with no array-of-tables at all is emitted as a single row of its top-level keys, which is a convenient way to flatten a plain config file.

FAQ