Introduction

Fig is a complete solution for managing settings across .NET microservices. Applications register a strongly typed settings class through the Fig.Client NuGet package. The Fig API stores those settings, and the Fig web application is where operators view, edit, and audit them.

Add with AI

Want an AI coding assistant to wire Fig into your app? Copy the prompt from Add Fig with AI and paste it into Cursor, Copilot, Claude Code, or similar.

A Fig 2.0-era product walkthrough is on the Videos page. The integration steps on this page reflect the current client API.

Quick Start

Pick the path that matches how you want to run Fig:

1. Fastest — clone the fig-quick-start repository. It is an Aspire host with Fig API, Fig Web, and a sample application.
2. Already using Aspire — add Fig to your AppHost with the Aspire integration.
3. Docker Compose — the compose file in the Fig repository deploys Fig API, Fig Web, and Fig MCP against SQL Server. It is a full deployment, not a one-command local demo.

Docker Compose

1. Copy .env.example to .env in the repository root and set fqdn, SA_PWD, FIG_DB_PWD, and the other required values. Optionally set FIG_MCP_PASSWORD if you want the MCP container to start authenticated.
2. From the repository root, run docker compose up.
3. Open Fig Web at http://localhost:7148 and log in with user admin / password admin. Change that password before exposing Fig Web beyond a local machine.

The API listens on http://localhost:7281. Compose maps API 7281:8080 and Web 7148:80.

Integrate a client

The same steps apply to a new or existing ASP.NET Core project.

1. Create a project if you need one:

dotnet new webapi

2. Add Fig.Client. Add a secret provider package for production.

3. Create a settings class that extends SettingsBase. Put the Fig client name on FigOptions, not on this class:

using Fig.Client;
using Fig.Client.Abstractions.Attributes;

public class Settings : SettingsBase
{
    public override string ClientDescription => "Example service settings";

    [Setting("My favourite animal")]
    public string FavouriteAnimal { get; set; } = "Cow";

    [Setting("My favourite number")]
    public int FavouriteNumber { get; set; } = 66;

    [Setting("True or false, your choice...")]
    public bool TrueOrFalse { get; set; } = true;
}

4. Register Fig as a configuration provider in Program.cs. Fig should be the last competing provider so it wins over appsettings.json.

using Fig.Client.ExtensionMethods;

var builder = WebApplication.CreateBuilder(args);

var loggerFactory = LoggerFactory.Create(b => b.AddConsole());

builder.Configuration
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddFig<Settings>(options =>
    {
        options.ClientName = "ExampleService";
        options.LoggerFactory = loggerFactory;
        options.CommandLineArgs = args;
        // Production: options.ClientSecretProviders = [new DockerSecretProvider(), new DpapiSecretProvider()];
        options.ClientSecretOverride = "be633c90-4744-48c3-82c4-7045b2e172d5"; // development only
    });

builder.Services.Configure<Settings>(builder.Configuration);
builder.Host.UseFig<Settings>();

UseFig<T>() registers Fig host workers (health, restart, custom actions, lookups). Do not call separate UseFigValidation / UseFigRestart APIs — they are obsolete.

5. Inject IOptionsMonitor<Settings> where the application should receive live updates.

6. Set FIG_API_URI to the Fig API address:

FIG_API_URI=http://localhost:7281

Comma-separated addresses are supported; the first reachable address is used for the process lifetime. Unset FIG_API_URI (or pass --disable-fig=true) to run without Fig.

7. Provide a client secret. Prefer a secret provider in production. ClientSecretOverride is for local development only.

See the examples in the source repository and Client Configuration for options, CLI flags, and offline modes.

Packages

Package	Use
Fig.Client	Add this to applications that Fig should manage
Fig.Client.Abstractions	Attributes and contracts for libraries that must not take a full client dependency
Fig.Client.Testing	Integration tests and display-script tests
Fig.Aspire	Aspire AppHost helpers for Fig API and Fig Web
Secret providers	Docker, DPAPI, Azure, AWS, Google

Fig MCP is a standalone container/app, not a client NuGet package. See the Fig MCP Server and the full package list.