"Converter" really means several different things
People search “YouTube converter” for at least four different jobs:
- Convert YouTube to MP4 — save the video as a portable MP4 file. The most common job; not really a “conversion” in the lossy sense because we never re-encode.
- Convert YouTube to MP3 — extract the audio and save as MP3 at a chosen bitrate. This is a real conversion (AAC source → MP3 output via LAME encoder).
- Convert YouTube to m4a — extract the audio without re-encoding. Direct copy of the source AAC bytes into a fresh m4a container. Lossless.
- Convert YouTube to SRT/VTT/TXT — extract the subtitles or transcript as a structured text file.
One paste handles all four jobs. The picker presents every option for the URL you paste; you choose the one you want.
Conversion vs extraction: what actually happens
The word “converter” covers two technically different operations:
- Pure extraction (no re-encode) — the source bytes get rewrapped into a different container without going through a decode/encode round. Output is byte-identical to the source. Examples: MP4 video output (we mux the YouTube video and audio streams unchanged), m4a audio output (we copy YouTube’s source AAC into a fresh m4a).
- Real conversion (re-encode) — the source gets decoded into raw audio/video samples, then re-encoded with a different codec at the chosen quality. Always lossy at some level. Example: MP3 export from YouTube’s AAC source.
The honest answer for “is this conversion lossy?” is: only when it has to be. We pick extraction over conversion whenever the source format is already what you want. MP4 output: extraction. m4a output: extraction. MP3 output: conversion (because no way around it). Subtitle output: extraction (text format rewrap).
Quality tiers that show up in the picker
For each output format the picker shows specific tiers, with file-size estimates inline:
- MP4 video — 144p, 240p, 360p, 480p, 720p, 1080p, 1440p, 2160p (4K), 4320p (8K). Codec is H.264 below 1080p, AV1 / VP9 above. Container is always MP4.
- m4a audio — one or two tracks per video, at the bitrate YouTube serves (typically 128–256 kbps AAC). The lossless option.
- MP3 audio — 128 / 192 / 320 kbps, encoded in your browser via LAME WASM. The portable option.
- SRT subtitles — with timestamps, for video editors and desktop players (VLC, Plex, etc.).
- VTT subtitles — web-friendly format for HTML5
<track>elements. - TXT transcript — no timestamps, deduplicated, suitable for reading or feeding into LLMs.
Why "browser-side converter" is the right answer in 2026
Almost every “online YouTube converter” on Google’s first page runs the actual conversion on their server: you submit the URL, their server fetches the video from YouTube, runs ffmpeg to convert, then streams the result back to you. That architecture has three downsides we deliberately avoid:
- Privacy. Their server sees every URL you convert. Some operators retain that data; some sell it to ad-targeting brokers; you have no way to audit.
- Cost passing-through to the user. Each server-side conversion costs the operator real money in bandwidth and CPU, which is why most converter sites cap at 1080p free and put 4K behind a paywall.
- Speed. Server-side conversion adds two network hops (you → them, them → you), instead of one (you → YouTube). On fast connections the round-trip delay is the bottleneck.
Browser-side conversion does the work on your CPU, with bytes flowing directly from YouTube to your machine. Privacy-preserving by architecture (not just by promise), cost-efficient (the operator only serves a few KB of metadata per video), and faster than server-side for anything above 480p on broadband connections.