Best TOML Formatter & Validator Online

Free Syntax highlighted · Error detection · Normalize spacing
Error
TOML INPUT
OUTPUT
// TOML output

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Why This Is the Best TOML Formatter Online

Format & Normalise TOML

Paste any TOML and get consistent key = value spacing, blank lines before section headers, and collapsed excess whitespace — without touching your data.

Validate Full TOML Spec

Detects duplicate keys, duplicate tables, invalid [[array of tables]], inline table errors, and malformed values — all without any server round-trip.

Cargo.toml & Config Files

Ideal for Rust Cargo.toml, Python pyproject.toml, and any application config that uses TOML. Handles all data types: strings, integers, floats, booleans, dates, and arrays.

Privacy First

All processing runs in your browser — nothing is uploaded to a server. Safe for Cargo.toml files containing private registry tokens or credentials.

Frequently Asked Questions

What is TOML?

TOML (Tom's Obvious Minimal Language) is a configuration file format designed to be easy to read due to its simple, obvious semantics. It maps unambiguously to a hash table and is widely used in Rust (Cargo.toml), Python (pyproject.toml), and many other ecosystems.

What does the TOML formatter change?

The formatter normalises spacing around = signs, ensures a blank line precedes every [section] header, and collapses multiple consecutive blank lines into one. It never changes key names, values, or their order.

Does it support Cargo.toml and pyproject.toml?

Yes. Both Cargo.toml and pyproject.toml are standard TOML files. This formatter fully supports [[bin]], [[dependencies]] array-of-tables, inline tables, multi-line strings, and all other TOML v1.0 constructs.

How is TOML different from YAML and JSON?

TOML is designed specifically for configuration files. Unlike JSON it allows comments. Unlike YAML it avoids indentation-based structure and ambiguous type inference. TOML has explicit types for integers, floats, booleans, dates, and strings, making it less error-prone for config use cases.

In-depth guide
YAML & TOML Config Guide
Kubernetes, Docker, Rust & Python configs
Read the guide