Add Subtitles to Video is a self-contained video editing and conversion workspace. Burn an SRT or ASS subtitle file directly into your video frames so the captions show in every player. Files are processed entirely in your browser with FFmpeg WebAssembly. Open the page, get the result, close the tab — that is the entire workflow.
From a technical standpoint, Add Subtitles to Video is JavaScript and FFmpeg compiled to WebAssembly running in your tab. The browser is the runtime; the page is the interface. Inputs accepted: MP4, WebM, MOV, MKV, AVI, FLV, and OGV. Maximum input size: 500 MB per run.
Add Subtitles to Video performs the transformation entirely inside the JavaScript runtime. Your file lives in the tab's memory while the engine works on it; the result lives in the tab's memory until the browser triggers the download. Both are released when the tab closes, the way every browser tab releases its memory.
Typical users of Add Subtitles to Video include creators trimming short clips, students submitting video assignments and educators editing lecture clips. The thread connecting all of them is the same: a focused video editing and conversion task that fits cleanly into a browser tab and benefits from a tool with sensible defaults and minimal setup.
Reach for Add Subtitles to Video when you need a predictable result on a single file. The page works on the first visit, the controls are visible without a menu, and the output is delivered the moment the engine finishes.
The hard constraints are easy to remember. Maximum input: 500 MB. Multiple files per run: no — one input at a time, by design, to keep results predictable. The same controls apply on every run.
If your task needs more than one step, chain Add Subtitles to Video with Video Text Overlay, Mute Video, and Video Thumbnail Generator. Each tool produces output that is a clean input to the next, so multi-step workflows are just a matter of opening the next tool in a new tab and continuing.
Add Subtitles to Video is built around steady iteration on a small set of options rather than feature creep. Every additional setting attracts a slightly different audience, but a long settings panel makes the common case slower for everyone. The current controls reflect what users of the tool actually use.
Add Subtitles to Video returns the result as `{name}-edited.{ext}`. If you are running multiple jobs, the output names will not collide as long as the input names differ. You can re-run with different settings as many times as you like; each run produces a fresh file with no caching trickery in between.
Some context on why Add Subtitles to Video exists in this form: modern File APIs, high-performance JavaScript engines, and well-maintained open-source libraries now make it possible to perform video editing and conversion work entirely in the browser. Add Subtitles to Video is built on top of that capability, which is why a single page can host the full pipeline.
Add Subtitles to Video produces deterministic output: the same input plus the same options always produces the same result. That predictability matters when the result has to match an upstream specification or be reproducible later.
If you want to get the most out of Add Subtitles to Video, three small habits help. Drag-and-drop is faster than the file picker once you get used to it. The keyboard shortcut for downloading the result is whatever your browser uses for "save link as," because the result is a normal download. And if you are working on a sensitive file, processing in an Incognito or Private window is a good extra layer — it leaves no trace in browser history when the tab closes.
Common gotchas worth flagging: Add Subtitles to Video only accepts MP4, WebM, MOV, MKV, AVI, FLV, and OGV, so if your file is in another format you will need to convert it first. The 500 MB ceiling is per-file, not per-session; you can run as many separate jobs as you like, but a single oversized input will be rejected on load.
Add Subtitles to Video is one of many single-purpose tools in the catalog. Each is built around the same single-page model. Use this one, close the tab, and come back the next time you need the same job done. None of the tools require prior knowledge of the others — each page is self-contained.
A WebAssembly build of FFmpeg loads in this page and re-encodes your video with the subtitle filter applied to every frame. The captions become permanent pixels — they show up in every player on every device, no separate subtitle file required.
Subtitle burn-in requires re-encoding every video frame, which is the most expensive operation FFmpeg performs. Server tools have native multi-threaded FFmpeg with hardware acceleration; WebAssembly is single-threaded, typically 5–10× slower. The trade-off is total privacy: your file never leaves your device.
SRT (the most common subtitle format) and ASS/SSA (Advanced SubStation Alpha, used for stylized anime fansubs). VTT files can be converted to SRT first using any text editor.
Burn-in (this tool) bakes the captions into the video pixels permanently — they cannot be turned off but they show in every player. Soft subtitles stay as a separate track and can be toggled, but they do not survive on most social media platforms or older players.
Yes — pick font size (14–48px), outline-only or boxed background style, and top or bottom positioning. The default style (white text with black outline at the bottom) is the broadcast standard.
Up to 500MB of video. Subtitle burn-in is one of the slowest operations because every frame is re-encoded — expect roughly real-time processing on a modern desktop, slower on mobile.
No. The audio stream is copied without re-encoding, so it is identical to the original. Only the video is re-rendered with the captions added.
No. The burn-in runs entirely in your browser tab. Nothing is transmitted, stored, or logged. Closing the tab erases the files from memory immediately.
Inputs are capped at 500 MB per file, which keeps memory usage stable across phones, tablets and older laptops. You can run Add Subtitles to Video as often as you need; every run produces a full-quality result.
Add Subtitles to Video can be used for personal and commercial work alike — there is no separate "business" licence to purchase. The output you generate is yours to use however you want, including in client deliverables, internal documents, or commercial products. Favtoo's only ask is fair, individual use; the tool is not designed to be embedded as a backend service or wrapped behind an API for resale.
No installation is needed. Add Subtitles to Video runs as a normal web page, with no browser extension, no native helper, and no separate desktop client to download. That is partly a privacy choice — extensions can request broad permissions, while a regular page is sandboxed by default — and partly a convenience one: you can use Add Subtitles to Video on any computer you have temporary access to without leaving anything installed on it.
Add Subtitles to Video only needs the standard web platform — file picker access for the inputs you choose to load, and optionally clipboard access if you copy the result rather than downloading it. There is no microphone, camera, geolocation or background-permission request, because none of those are needed for the work the tool does. Some browsers prompt the first time WebAssembly is compiled; that is a normal one-time event, not specific to Favtoo.
Add Subtitles to Video is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.
Failures usually fall into one of three buckets: the input is in an unsupported format, the input is over the size cap, or the input is structurally malformed (a truncated download, a partial export, or a stream the engine does not recognise). The first two are easy to confirm — check that your file is one of MP4, WebM, MOV, MKV, AVI, FLV, and OGV and that it is below 500 MB. For the third, opening the file in its native viewer first is the fastest way to confirm the source is intact.
Add Subtitles to Video is a static page running an open-source engine in your browser, so a typical corporate firewall does not get in the way as long as it allows JavaScript and WebAssembly to load from Favtoo. For teams that need to host it themselves on an internal network, the underlying engine (FFmpeg compiled to WebAssembly) is open-source and can be packaged into a private build with the same behaviour. Reach out via the Contact page if that is something you are exploring.
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. Add Subtitles to Video sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common video editing and conversion operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
Favtoo keeps no copy of your file because Favtoo never receives your file. Add Subtitles to Video runs entirely in your browser, the input is held only in your tab's memory, and closing the tab discards it. There is no opt-in cloud history, no "recent jobs" panel synced to an account, and no server-side retention to configure — the architecture simply has nowhere for your file to be stored.
Video to GIF
Convert any video clip to an animated GIF entirely in your browser. Pick the start, length, frame rate, and width — your file is processed locally with FFmpeg WebAssembly and never uploaded.
Screen Recorder
Record your screen, a window, or a browser tab directly in your browser. Optionally include system audio and your microphone. Capture, preview, and download the video without installing any app — and without uploading anything.
Webcam Recorder
Record your webcam directly in your browser with optional microphone audio. Pick the resolution (480p, 720p, or 1080p), frame rate, and mirror mode, then capture and download the result without installing any app.
Screen + Webcam Recorder
Record your screen with your webcam composited into a picture-in-picture corner — perfect for tutorials, course videos, demos, and reaction recordings. Pick the camera position, size, and audio sources, then capture and download in your browser.
Video Slideshow Maker
Turn a stack of photos into an MP4 slideshow with per-slide durations, crossfades, and an optional soundtrack. Pick the resolution (up to 1080p), frame rate, and transitions, then download a single MP4 — all processed in your browser with FFmpeg WebAssembly.
Video from Images + Audio
Combine a stack of photos with a music track or narration into a single MP4 video. Pick the resolution, per-slide duration, transitions, and let the slideshow length match the audio. All processed in your browser with FFmpeg WebAssembly.
Video Trimmer
Set precise in and out timestamps, snap to keyframes when needed, and document handles for social-safe cutdowns.
Video Splitter
Split any video into 2–10 equal-length pieces, packaged as a downloadable ZIP. Files are processed entirely in your browser with FFmpeg WebAssembly using lossless stream-copy.