# Build brief — a focused alternative to AudioFetcher

> **Verdict:** Partly, if you narrow it · **Buildability:** 72/100 · **Category:** Audio Video
> **Source:** https://www.canitbevibecoded.com/audiofetcher
> Independent editorial assessment from Can It Be Vibe Coded? Not affiliated with, endorsed by, or derived from AudioFetcher. Verify current pricing and capabilities before acting.

## Context

**AudioFetcher** — Paste a YouTube or playlist link, convert to MP3, and download · Pro adds 320 kbps and priority queue. It currently costs $6/mo.

The core loop is genuinely one-shottable: a small local UI, yt-dlp for the fetch, ffmpeg for the encode, files land in a folder. What is not simple is everything that makes a public converter feel reliable week after week · YouTube bot checks, cookies/PO tokens, geo blocks, fair queues, abuse protection, and a hosted path so non-technical people never open a terminal. Build the personal script; do not expect one prompt to replace a maintained public service.

This brief describes a focused, single-operator replacement for the part of AudioFetcher that is genuinely reproducible. It is deliberately narrower than the product it replaces, and it says so in writing. Build the useful core; do not pretend to have rebuilt the rest.

## What you are building

Accept a YouTube URL or playlist, download audio with yt-dlp, encode MP3 with ffmpeg, and save the file locally.

- Build a focused single-user workflow with real persistence, search, and export.
- A responsive interface with real empty, loading, success, and error states.

## Requirements

### Functional

- Python or Node.
- Yt-dlp.
- Ffmpeg.
- Optional cookies or residential proxy if YouTube blocks datacenter IPs.

### Non-functional

- Accessibility: semantic markup, labelled controls, visible focus, and reduced-motion support.
- Security: server-side secrets, validated input, and no credentials in the client bundle.
- Reliability: retries with backoff on external calls, and a clear failure state when a provider is down.
- Portability: the operator can export their data and leave without losing it.

## Implementation brief

Build me a personal YouTube-to-MP3 tool to replace AudioFetcher for one user on my laptop. Requirements:

- Python 3.11 + a tiny localhost Flask or Starlette app; one page with a URL field,
  quality select (128 / 192 / 256 / 320 kbps), and a Convert button.
- On submit, shell out to yt-dlp to pull best audio only, then ffmpeg to CBR MP3 at the
  chosen bitrate. Write files into ./downloads with a safe title filename.
- Support a single video URL and a playlist URL. For playlists, show a checkbox list of
  titles first (yt-dlp --flat-playlist --print), then convert only checked items one by one
  with a simple progress log on the page (SSE or polling).
- Put YT_COOKIES_FILE and optional HTTP_PROXY in .env; pass them to yt-dlp when set.
  If yt-dlp returns LOGIN_REQUIRED or bot-check text, show that error plainly and tell me
  to export cookies from a logged-in browser.
- Cap each job at 3 hours of media; reject live streams. No accounts, no cloud, no queue
  service for other users · this is just me.
- Out of scope: multi-tenant fair queues, Stripe/Pro billing, magic-link auth, public
  abuse protection, mobile apps.
- README: install yt-dlp + ffmpeg, how to export Netscape cookies, and a blunt note that
  YouTube blocks many datacenter IPs so a home machine or cookies may be required.

## Delivery standard

- Inspect the repository first, then write a short implementation plan before writing code.
- Deliver the smallest complete end-to-end workflow first; every primary control must work against persisted data.
- Use real validation and storage; never substitute fake dashboards, decorative controls, hard-coded success states, or mock integrations.
- Include responsive layouts plus genuine empty, loading, success, validation, and failure states.
- Keep secrets server-side in environment variables, provide .env.example, and never commit credentials or user data.
- Add structured logs around every external call and return actionable errors without leaking sensitive details.
- Write unit tests for the core logic and one automated test of the main user journey.
- Finish with a README covering setup, architecture, data location, backups, tests, deployment, and known limitations.

## Acceptance criteria

- [ ] A clean install starts the app using only the README and .env.example.
- [ ] The primary journey works from first visit through saved result, reload, edit, export, and deletion where applicable.
- [ ] Invalid input, missing configuration, provider failure, and an empty database each have a usable state.
- [ ] The interface works at 390px and 1440px, is keyboard navigable, and shows visible focus on every control.
- [ ] Tests, type checking, linting, and a production build all pass with no ignored failures.
- [ ] No part of the interface implies a live integration, security guarantee, or scale capability that was not actually built and verified.

## Non-goals

Do not build these, and do not claim to have replaced them:

- Hosted UI for non-technical users.
- Playlist preview with per-track checkboxes.
- Priority queue and 320 kbps Pro path.
- Someone else fighting YouTube bot checks, PO tokens, and geo blocks.
- The last 20 percent is sync, migration fidelity, speed, and edge cases.

## What you still own after launch

- Run migrations, backups, restores, and dependency updates.
- Test the critical journey after every model, API, or hosting change.
- Monitor failures and fix the edge cases a first prompt will miss.

## Risk

**Manageable.** A personal version is realistic if you test the critical journey and keep reliable backups.

Editorial confidence in this assessment: high. No independent one-shot implementation is linked yet.

## Prior art

Working open-source software you can read, fork, or borrow from before starting:

- [yt-dlp](https://github.com/yt-dlp/yt-dlp) — The actual download engine almost every converter wraps. Best DIY path is using it directly
- [cobalt](https://github.com/imputnet/cobalt) — Open-source multi-service media downloader with a self-hostable API and web UI
- [youtube-dl](https://github.com/ytdl-org/youtube-dl) — Older predecessor; still useful context for how long this cat-and-mouse has run

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Generated by [Can It Be Vibe Coded?](https://www.canitbevibecoded.com) · Full report: https://www.canitbevibecoded.com/audiofetcher