pysize

A bundlephobia-style size explorer for PyPI packages. Type a package — requests, or headroom-ai[all] with extras — and see its install size: the wheel plus every dependency, deduplicated, sorted largest-first. Click any dependency to drill into it; the URL is shareable.

It resolves entirely against the public PyPI JSON API — no installing, no sandbox.

Quick start

make run        # or: uv run main.py
# open http://127.0.0.1:8731

That's it — uv reads the dependencies from the inline script header in main.py and runs the server. Run make help for the other targets (verify, ping, deploy, logs, clean).

How sizes are measured

The total is the download size of one wheel per package (prefers the py3-none-any wheel), summed across the package and the full deduplicated dependency set. It is a close analog to bundlephobia's number, not an exact on-disk install size — see docs/accuracy.md.

API

GET /api/size?pkg=<requirement>

<requirement> is any PEP 508 requirement: flask, httpx, boto3, headroom-ai[all], django>=5. Response:

{
  "name": "Flask",
  "version": "3.x",
  "self_size": 612345,        // bytes, the package's own wheel
  "total_size": 618000,       // bytes, deduplicated total
  "dep_count": 6,             // unique dependencies
  "packages": [               // each unique dependency, largest first
    { "name": "Werkzeug", "version": "3.x", "size": 234567 },
    ...
  ]
}

Documentation

• How it works — the resolver and the two cache layers.
• Accuracy — how results are verified against uv, and the known gaps.
• Deployment — Ansible playbook to run it behind nginx as a systemd service.

Verifying correctness

verify.py resolves random popular packages and diffs the dependency set against a real resolver (uv pip compile):

uv run verify.py 5          # 5 random popular packages
uv run verify.py flask boto3 # specific ones

Project layout

| Path | What | |------|------| | main.py | FastAPI app: resolver, caching, API, serves the page | | index.html | Single-page frontend | | verify.py | Correctness check against uv | | ansible/ | Deployment playbook (nginx + systemd) | | Makefile | Common tasks (make help) | | docs/ | Documentation |

Status

A proof of concept. It resolves the latest version satisfying each specifier rather than producing a fully locked resolution, and reports wheel download size. Good enough to compare packages at a glance; not a substitute for actually installing.