Tomlyn

High-performance TOML 1.1 for .NET: lexer/parser, roundtrippable syntax tree, and a System.Text.Json-style object serializer.

Get started Serialization Low-level APIs GitHub

dotnet add package Tomlyn

Available on NuGet - net8.0, net10.0, netstandard2.0

Looking for YAML support? Check out SharpYaml.

Familiar API

Tomlyn is intentionally shaped like System.Text.Json: TomlSerializer, TomlSerializerOptions, source-generated contexts, and a converter pipeline.

Two layers

Use the syntax/model layer for lossless parsing, source spans, and tooling. Use TomlSerializer to map TOML into .NET objects.

NativeAOT ready

Reflection fallback can be disabled. For NativeAOT and trimming, use generated metadata via TomlSerializerContext and TomlTypeInfo<T>.

JSON attribute interop

Most common System.Text.Json.Serialization attributes work out of the box (for example [JsonPropertyName], [JsonIgnore], [JsonConstructor]).

Quick example

using System.Text.Json;
using Tomlyn;

public sealed record Person(string Name, int Age);

var options = new TomlSerializerOptions { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };

var toml = TomlSerializer.Serialize(new Person("Ada", 37), options);

// name = "Ada"
// age = 37

var person = TomlSerializer.Deserialize<Person>(toml, options);

Next: read the Getting started guide.