Build your own API in Python: a private link-saver for every device

Here's what you're building. linkstash saves web links with a title, tags and a note. Other programs (a script, a web page, an automation, your phone) talk to it over HTTP:

• POST /links saves a link
• GET /links lists them, with ?tag=, ?q= (search) and paging
• GET /links/3, PATCH /links/3 and DELETE /links/3 read, edit and delete one
• GET /health tells a monitor it's alive. Everything under /links needs your API key.

Every file is in the starter kit: linkstash.zip (105KB). You can unzip it and follow along, or type each file as you go. Typing is slower but you'll learn more. Either way, start by making the project:

uv init --bare --python 3.12 linkstash
cd linkstash
uv add "fastapi[standard]" pydantic-settings

--bare makes just a pyproject.toml (the project's settings file) and nothing else. fastapi[standard] is FastAPI plus the extras its install guide ↗ recommends: the fastapi command, the Uvicorn web server and the httpx client. pydantic-settings is already among those extras, but you'll import it yourself, so it's listed by name. uv puts everything in a .venv folder and records exact versions in uv.lock.

Open pyproject.toml in your editor and add the last two lines, so the fastapi command always knows where your app lives. The FastAPI CLI docs ↗ recommend this over typing a file name each time:

[project]
name = "linkstash"
version = "0.1.0"
requires-python = ">=3.12"
dependencies = [
    "fastapi[standard]>=0.143.0",
    "pydantic-settings>=2.15.0",
]

[tool.fastapi]
entrypoint = "main:app"

Now the smallest possible FastAPI app, straight from FastAPI's first steps ↗. Save it as main.py in the linkstash folder:

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
async def root():
    return {"message": "Hello World"}

Start the development server:

uv run fastapi dev

⚡️ Starting FastAPI in development mode

🐍 Using import string: main:app

🌐 Server started at http://127.0.0.1:8000
   Documentation at http://127.0.0.1:8000/docs

 Logs:

INFO:     Will watch for changes in these directories: ['C:\\Users\\you\\linkstash']
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [37696] using WatchFiles
INFO:     Started server process [26332]
INFO:     Waiting for application startup.
INFO:     Application startup complete.

Open 127.0.0.1:8000 ↗ in your browser, then 127.0.0.1:8000/docs ↗. That second page is the interactive documentation FastAPI builds from your code. It updates itself every time you add an endpoint.

Two things about fastapi dev: it restarts by itself when you save a .py file, and it only listens on 127.0.0.1, so nothing else on your network can reach it. Press Ctrl + C in the terminal to stop it.