Video Merger is part of a collection of single-purpose video editing and conversion tools. Combine multiple video clips into a single MP4 in your browser. Drop in MP4, WebM, MOV, MKV, AVI or FLV files, drag to reorder them, pick a target resolution and frame rate, and merge — all locally with no uploads. Each tool is intentionally narrow — it does one thing well rather than offering many overlapping features — which makes the common path predictable and the result easy to verify before you download or copy it.
Internally the tool runs on FFmpeg compiled to WebAssembly — the same processing stack used by professional desktop pipelines, just compiled for the browser. MP4, WebM, MOV, MKV, AVI, FLV, and OGV files are accepted natively. 500 MB is the practical ceiling, set so the tool stays responsive on phones and older laptops.
Common audiences for Video Merger include teams compressing demo recordings and creators trimming short clips, but plenty of people land on the page through a one-off search and never come back — that is also fine. The tool is built to be useful even when you only ever need it once.
Video Merger is structured so the question "where is my file processed?" has a single answer: in your browser tab. The engine, the controls, and the result panel are all on one page. Navigating away or closing the tab clears the page's memory the way it does for every other tab.
The right moment to reach for Video Merger is when you have a focused video editing and conversion job that fits inside a browser tab. Open the page, drop in the file or paste your input, choose the options that matter, and the tool returns the result.
When the job finishes, Video Merger hands you the result as `{name}-edited.{ext}`. Filenames are derived from your input where possible, so a quick batch of jobs leaves you with a tidy folder rather than a pile of generic "output (3)" files. Nothing is auto-saved on Favtoo's side because nothing was ever sent there.
The 500 MB ceiling on input size is the only fixed limit. Output files are produced in standard formats that every common viewer recognises, and the tool runs the same way regardless of how many times you have used it during the session.
Once you have used Video Merger, the natural next steps depend on what you are doing with the result. Common follow-ups include Video Trimmer, Video Speed Changer, and Video Cropper. These are surfaced on the page so you do not have to hunt the catalog manually.
The transformation in Video Merger is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
Video Merger is structured around the idea that a useful tool should be its own page. Open the page, do the work, close the tab — the page is the entire product. There is no onboarding flow because there is nothing to onboard into.
Video Merger is built around the moment of need: a focused page you open when you have a specific task, complete the task, and close. The catalog contains many adjacent tools so the same model serves the surrounding parts of a typical video editing and conversion workflow.
A few practical tips that experienced users of Video Merger pick up over time. First, keep your default browser updated — the engine relies on standard web APIs and newer browser versions are noticeably faster than ones from a few years ago. Second, close other heavy tabs before processing a large input; the engine shares CPU and memory with whatever else is open. Third, if you re-run the same kind of job often, your last-used settings are remembered for the rest of the tab session, so subsequent runs are essentially one click.
Common gotchas worth flagging: Video Merger 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.
That is essentially everything Video Merger does and how it does it. Open the tool above, drop in your input, and the work happens in the page. If you find yourself reaching for it often, bookmark the page — it loads quickly on subsequent visits, and your most-recent settings are remembered for the rest of the session.
Drop your clips into the box above, drag them into the order you want, choose a resolution (1080p, 720p, square or 9:16) and a frame rate, then click Merge. The tool produces a single MP4 you can download — all without uploading anything.
Yes. The merger accepts MP4, WebM, MOV, MKV, AVI, FLV and M4V in any combination. Each clip is decoded, scaled to the target resolution with letterboxing if needed, then re-encoded into a clean H.264/AAC MP4 so the result plays everywhere.
No. Everything runs in your browser via WebAssembly. Your clips are read into memory inside this tab and the merged file is generated locally. Nothing is sent to a server, stored, logged or shared, and closing the tab erases the files from memory.
Server-based mergers run native FFmpeg on multi-core machines with hardware acceleration. This tool ships a single-threaded WebAssembly build that runs entirely on your CPU inside the browser sandbox — typically 5–15× slower than native — but in exchange your videos stay completely private and you avoid upload time on slow connections.
You can merge up to 12 clips at a time, with a combined size of about 500 MB. For very long projects, merge in two passes — combine groups of clips first and then merge the resulting files.
All clips are scaled to the target resolution you pick (e.g. 1920×1080) and letterboxed with black bars to preserve their aspect ratio. This guarantees a consistent output even when sources have different shapes — vertical phone footage will sit centred inside a horizontal frame, and vice versa.
Audio tracks from each clip are resampled to a common 48 kHz stereo format and concatenated alongside the video. If one or more clips have no audio at all, the tool automatically retries with audio disabled so the merge still succeeds.
No watermark, no account, no email, no payment — the output is a clean MP4 that you own outright.
Favtoo keeps no copy of your file because Favtoo never receives your file. Video Merger 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 Merger 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.
No installation is needed. Video Merger 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 Video Merger on any computer you have temporary access to without leaving anything installed on it.
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.
Your file is processed inside your browser by FFmpeg compiled to WebAssembly. The engine reads the file's bytes from your tab's memory, computes the result, and writes the result back into the tab. You can confirm what the page does by opening developer tools and watching the Network tab during a run — the requests you see are for the tool's static assets only.
Video Merger processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Video Merger runs in any modern mobile browser — Safari, Chrome, Firefox and the in-app browsers in most messaging apps all support the underlying APIs. Performance depends on the device: a recent phone handles typical inputs nearly as fast as a laptop, while older devices may take a few seconds longer near the 500 MB ceiling. The interface lays out cleanly on small screens, so you do not need to pinch-zoom to see the controls.
Video Merger 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.
Video Merger 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.
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.