Meet an upload requirement
Prepare a clip for a CMS, learning platform, ticket system or social workflow that accepts only certain containers or codecs.
Video Converter
Convert MP4, WebM, MKV and MOV videos in your browser, with quality presets, optional codec controls and an output preview.
Read the full guide1. 1. Select video
Drag and drop your video file here
or click to browse
Supported formats: MP4, WebM, MKV, MOV
Max file size: 2GB
Sample video:
2. 2. Conversion settings
Select the container required by the destination. Codec availability depends on the chosen format and browser.
Higher quality usually produces a larger file and takes longer to encode.
Leave Auto to select a compatible codec for the output container.
Leave as Auto to use the best compatible codec.
3. 3. Convert
Local files stay on this device. URL mode downloads the remote media into the browser before conversion.
4. 4. Result
Your converted video will appear here
Select a video and start conversion to create a result.
- File name
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- Format
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- Size
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- Duration
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- Resolution
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- Codecs
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AppKiro does not upload or store local videos. The original file is not modified.
How do I convert a video format online?
Add an MP4, WebM, MKV or MOV file, or provide an accessible direct media URL. Choose the target format and quality, adjust advanced settings only when needed, then convert and download. Changing format does not recover detail missing from the source.
Common reasons to convert a video
Improve playback compatibility
Create a practical MP4 for general sharing or a WebM file for a modern web page.
Prepare an editing handoff
Move footage into an MKV or MOV workflow when an editor or production application expects that container.
Reduce delivery size
Lower resolution or bitrate when quick transfer matters more than keeping every source detail.
Test media behavior
Generate controlled samples for browser, QA, codec or player compatibility checks.
How to convert a video in the browser
- 1
Choose the source
Select a supported local video or enter a direct URL that permits CORS and byte-range requests.
- 2
Pick the destination format
Use MP4 for broad sharing, WebM for modern web delivery, MKV for flexible technical workflows or MOV for common editing pipelines.
- 3
Set quality and compatibility
Start with Auto codecs and a balanced or high preset. Open advanced settings only when the destination specifies resolution, FPS or bitrate.
- 4
Run the conversion
Keep the page open while the browser reads, decodes, encodes and packages the media tracks.
- 5
Preview and download
Check duration, resolution, codecs and file size, then save the new file. The original remains unchanged.
Which output format should you choose?
MP4
General sharing, websites, phones and office apps
Usually the safest first choice when no special workflow is required.
WebM
Modern web delivery and compatible transparent VP9 workflows
Efficient for browsers, but some desktop and editing workflows may prefer MP4 or MOV.
MKV
Archives, testing and flexible technical media tracks
Powerful container support, though playback in everyday apps is less universal.
MOV
Editing and media production pipelines
Common in creative applications; final compatibility still depends on the codecs inside.
Quality, resolution and bitrate explained
Quality preset
A preset coordinates several encoder choices. High preserves more detail; Balanced is a useful default; Small file trades detail for easier delivery.
Resolution
Reducing width and height can cut file size substantially. Increasing resolution does not create real detail that was absent from the source.
Frame rate
Keeping the source FPS avoids unnecessary motion changes. Lower FPS can reduce size for slides or slow screen recordings.
Video bitrate
Bitrate controls how much data is available per second. Too little may cause blocking, blur or color banding.
Codec
A container such as MP4 or WebM holds encoded tracks. The codec determines how those tracks are compressed and which players can decode them.
A reliable default workflow
- 1
Choose MP4 and Balanced or High quality for ordinary sharing.
- 2
Leave codecs on Auto unless the destination specifies a codec.
- 3
Keep the original resolution and FPS for the first attempt.
- 4
Lower resolution or bitrate only when the output is too large.
- 5
Use WebM with a compatible alpha codec only when transparency is required.
- 6
Play the downloaded file in the actual target browser, device or application.
Local processing and remote URLs
A video selected from your device is decoded and encoded in the browser and is not uploaded to AppKiro. URL mode necessarily retrieves the remote file from its host; the URL must point to readable media and allow browser access through CORS and byte-range requests.
Important limitations
- •Browser codec support varies by browser, operating system, hardware acceleration and selected container.
- •A 2 GB interface limit does not guarantee that a very large file will fit in available memory during encoding.
- •Conversion can change container, codec, resolution, frame rate or bitrate, but cannot restore missing source detail.
- •A generated file may be downloadable even when the current browser cannot preview that exact codec combination.
- •Transparent output works only with compatible source data, container, codec and browser encoder support.
Frequently asked questions
Are local videos uploaded during conversion?
No. Files selected from your device are decoded and encoded in the browser. Network access is used only when you choose a remote URL or when the app loads required conversion components.
Why can a video URL fail even though it opens in a tab?
A browser tool needs a direct media URL whose server permits CORS and byte-range requests. A streaming page, protected CDN or storage bucket may open normally yet block programmatic reading.
Which output format is the safest default?
MP4 is usually the most practical choice for general sharing. Choose WebM for modern web delivery, MKV for flexible technical workflows, or MOV when an editing pipeline expects it.
Why are some codec options missing or failing?
Encoding support depends on the browser, operating system, hardware acceleration and container. Only combinations the runtime can actually encode should be enabled.
Does conversion improve a low-quality source?
No. Re-encoding can change compatibility and size, but it cannot recreate detail that the original video does not contain.
Why is the converted file larger?
A higher quality preset, bitrate, resolution or less efficient codec can increase size. Lower resolution or bitrate when delivery size matters more than fidelity.
Can the converter preserve a transparent background?
Only when the source has alpha data and the browser can encode a compatible combination, commonly VP9 in WebM or MKV. Otherwise choose a non-transparent output.
What is the practical file size limit?
The interface caps local input at 2 GB, but available memory may impose a lower practical limit. Long videos are safer at a lower resolution or bitrate.
Why can the output fail to preview?
The browser may be able to create or download a container and codec combination that its built-in player does not decode. Test the downloaded file in the intended destination.
Will the original video be overwritten?
No. The converter creates a new file with a new extension. It does not rename, watermark or modify the source file on your device.
Related video tools
Video Compressor
Reduce file size when you do not need to change the container.
Record Live Media
Record a screen, camera or microphone before converting the result.
Video to GIF
Turn a short section into an animated GIF for simple previews.
Media Metadata Viewer
Inspect the source or output container, codecs, duration and dimensions.