# D1 03 Swagger

> Adds Swagger/OpenAPI UI to the up-api .NET project and redeploys it. Use when the user asks for Day 1 step 4 of the CRUD drill, or asks to add API docs / Swagger to up-api.

- Skill: `softinter-chiangrai/d1-03-swagger` (Agent Skill)
- Install (CLI): `npx skillmds@latest add softinter-chiangrai/d1-03-swagger`
- Raw SKILL.md: https://api.skillmd.com/api/skills/softinter-chiangrai/d1-03-swagger/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: softinter-chiangrai (https://skillmd.com/u/softinter-chiangrai)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/softinter-chiangrai/d1-03-swagger

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# Day 1 · Step 3 — Swagger

Check `up-api/Program.cs` first — recent `dotnet new webapi` templates already scaffold OpenAPI
(`AddOpenApi()` / `MapOpenApi()`). If Swagger UI specifically is wanted (not just the raw OpenAPI JSON),
add Swashbuckle:

```Run bash
cd up-api
dotnet add package Swashbuckle.AspNetCore
```

In `Program.cs`:
```csharp
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
// ...
app.UseSwagger();
app.UseSwaggerUI();
```