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TOML to JSON

Convert TOML 1.1 to JSON with explicit policies for large integers, precise date/time tokens and non-finite values. Review configuration locally.

Choose your path

Built around the job you need to finish

Convert TOML 1.1 configuration with correct table grammar and explicit integer, temporal and non-finite JSON policies.

Service configuration developer

Retain every array-table entry and nested key.

Convert two servers, inline tables and multiline strings; test duplicate keys.

All entries remain and invalid duplicate definitions produce no partial output.

Precision-sensitive data engineer

Keep unsafe identifiers and original timestamp precision.

Compare unsafe-integer policies, exact offset timestamps and typed temporal records.

Large integers do not round; fractional digits and local/offset distinctions are explicit.

Mobile configuration maintainer

Recover from invalid dates without hidden normalization.

Try February 30, correct the date, reset policies and export current JSON.

Impossible dates are refused and source edits clear stale results.

Authoritative checks for this tool

Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.

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Reference & details

How it works

Grammar-aware configuration

Pinned smol-toml 1.8.0 parses TOML 1.1 tables, dotted keys, arrays of tables and string forms. Duplicate keys and malformed syntax are rejected rather than overwritten or skipped.

Preserve temporal tokens

After grammar validation, date/time tokens outside strings and comments are protected and parsed again. Calendar checks prevent rollover; source digits, fractional seconds and offsets remain strings or explicit typed records.

Bound integer and float mapping

Safe integers become numbers; unsafe integers become decimal strings or are refused. Infinity and NaN require explicit string labels. Floats use binary64, not arbitrary decimal precision; comments and source formatting are not retained.

Updated: August 2026

Example Scenarios

A developer converts two [[servers]] entries and verifies both ports survive, including inline numeric comments and nested tables.

A data engineer keeps 9007199254740993 as an exact decimal string and checks a sub-millisecond timestamp without silently rounding it.

A maintainer chooses typed date/time records, tests an impossible calendar date, then recovers using a valid example and reviews the JSON output.

FAQ

The pinned parser targets TOML 1.1, including multiline strings and omitted seconds in time values. This workspace adds explicit size, type and date validation limits; it is not a certification of every ecosystem extension.

Values outside the safe integer range of common JSON consumers can round when read as numbers. Exact decimal strings are the default; you can instead refuse such input. Base spelling and integer negative zero are not retained.

Original date/time tokens retain fractional digits and offset spelling. Local values gain no inferred timezone. Typed records distinguish local date, local time, local date-time and offset date-time; unsupported leap seconds are refused.

No comments or TOML formatting are exported. Non-finite values are rejected unless you explicitly choose labels. Floats use binary64, so decimal spelling and arbitrary decimal precision are not preserved.

One million input characters, two million output characters, 64 nesting levels, 100,000 values and a ten-second worker timeout. No automatic source save or upload. Use UTF-8 import and result-only copy/download; first engine load may need a connection.

About TOML to JSON

Configuration conversion is a type-mapping decision. Review integer and temporal policies, then convert; unsupported or invalid data produces no partial JSON.