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toml → json · @iarna/toml · tables · arrays · live

Convert TOML to JSON

Parse modern TOML configuration files into pretty JSON. Tables, inline arrays, dates and typed values all survive the round trip. Everything runs locally.

TOML → JSON
Input
151 B
10 lines
Output
8 B
1 lines
Status
ready
live
Ratio
0.05×
out/in
input · toml
output · json
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Quick Start

How to convert TOML to JSON

Uses the @iarna/toml parser to read tables, inline arrays, datetime literals and typed scalars, then emits pretty JSON suitable for diffs or tooling.

  1. 01

    Paste TOML

    From a Cargo.toml, pyproject.toml, or any modern config file.

    Parsing is strict-but-tolerant — comments and trailing commas are accepted on input where the source format historically permits them; output stays canonical.

    inputstricttolerantliveparse
    input · sourcetoml · live
    [owner]
name = "Jane"
    loaded · parsedtarget · ready
  2. 02

    Tables → objects

    Each [section] becomes a nested object; dotted keys nest deeper.

    Conversion preserves type information where the target supports it (numbers stay numeric, booleans stay boolean) so the destination parser never has to re-coerce.

    tablestype-preservinglosslesslivememoised
    section · optionsobject · live
    { "owner": { "name": "Jane" } }
    options applied · liveround-trip
  3. 03

    Typed values

    Numbers, booleans, dates and arrays all keep their JSON-native type.

    Re-encoding is idempotent: running output back through the same converter produces the same bytes, which keeps round-trips git-friendly.

    typesidempotentround-tripdiff-cleandeterministic
    type · convertedpreserve · ready
    "ports": [8001, 8002]
    converted · livediff-clean
  4. 04

    Copy or download

    Drop the JSON into your tooling, diff against a reference, or pipe through jq.

    Copy writes via navigator.clipboard.writeText; downloads use the target’s native MIME so editors apply the right syntax highlighting on open.

    exportclipboardtarget MIMEblobclient-side
    ok · copiedready · done
    ✓ Copied
    shipped · ready to shipsuccess
Pro tips

Converting between formats, safely

Pick the strictest source format

Lossy formats hide bugs. Choose JSON or YAML as your source-of-truth, convert downstream as needed.

Round-trip in CI

If your converter is idempotent, your CI can verify A → B → A equals the original. Catches subtle data loss.

Numbers vs strings differ

YAML/TOML have a number type; CSV doesn’t. Quote IDs in CSV to keep leading-zero values intact.

Watch character encoding

Source format may be Latin-1 / Windows-1252; target should be UTF-8. Convert encoding before structure.

Preserve comments where you can

YAML and TOML support comments. Don’t silently drop them — they often encode intent.

Schema-aware beats blind

Use a schema to guide conversion. Field types, required-ness, and defaults survive better with structure.

Related toolsJSON to TOMLXML to JSONYAML to JSONINI to JSONJSON FormatterJSON Validator
Use Cases

When to convert TOML to JSON

Audit Rust/Python config, feed CI dashboards, diff revisions.

Cargo & pyproject

Surface Rust or Python dependency graphs as JSON for analytics. Type information survives: numbers stay numeric, booleans stay boolean, strings stay strings. The destination parser doesn't have to re-coerce, which avoids the "'true' becomes "true"" bug class.

round-trip safe

App config diff

Compare two environments by diffing JSON output side-by-side. Run output back through the inverse converter to verify idempotent round-trips in CI. A → B → A should produce byte-identical input — if it doesn't, you've found data loss.

type-preserving

Schema validation

Run JSON-schema tooling against your TOML configuration. Comments and metadata survive where the target format supports them (YAML, TOML, HCL). The tool doesn't silently drop intent-encoded annotations, which keeps your config self-documenting.

schema-aware

Migrate formats

Stage a TOML → JSON conversion before swapping config systems. Pair with a schema (JSON Schema, OpenAPI, Zod, Pydantic) to catch shape drift on either side. Catch breaking changes at conversion time rather than at runtime in production.

lossless

CI dashboards

Feed JSON into status boards that don't know TOML. Output respects target-format conventions: quoting in CSV, indent in YAML, brackets in JSON. Existing parsers don't need patches, and the result drops into legacy pipelines unchanged.

diff-clean

API delivery

Serve project metadata to clients in the JSON they expect. Encoding-aware: handles UTF-8 vs UTF-16 vs Latin-1 / Windows-1252 transparently. The character-set surprise that breaks "works on my machine" doesn't apply here.

spec-grade
FAQ

Frequently asked questions

The @iarna/toml parser tracks TOML v1.0.0 — including inline tables, mixed-type arrays of tables, and full datetime support.
Yes — RFC 3339 datetimes are emitted as ISO strings in the JSON output.
You'll see the parser's error message inline. Fix the offending line and the live output updates.
Pair this with our JSON to TOML converter to go the other way. Mind that comments don't survive the round trip.
No. The whole conversion runs locally in your browser.
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