Help center

The most common causes, in rough order of how often they happen:

• The file is over 30 MB. The website rejects larger inputs to reduce browser memory failures. The downloadable version removes that check, but it remains limited by browser and device memory.
• The browser ran out of memory mid-conversion. This usually only happens on very long videos or very high-resolution images. Try a smaller file, a lower output resolution, or switch to the local version.
• The source file is corrupted. Open it in its native app first to confirm it works. If it does not, the converter cannot recover it.
• The codec inside the container is not supported by the selected browser or output path. An accepted extension does not guarantee that every codec variant will decode.
• You are on an old browser. day2dayfile needs current Canvas, Web Audio, MediaRecorder, and WebAssembly features; exact format support still varies between current browsers.

If none of these explain it, email us with the file type, the browser you are using, and the step that failed.

Memory. The web converter runs everything inside a browser tab, which has a much smaller memory budget than a native app. Loading a 50 MB video file and decoding it in JavaScript can quickly hit limits, especially on phones and lower-end laptops.

The 30 MB cap limits the risk of a browser tab exhausting memory; it is not a guarantee that every file below the limit will succeed. The downloadable version removes this artificial check, but browser and device memory still impose practical limits.

Images: the picker explicitly supports JPG, PNG, WebP, and QOI. Other browser-decodable images may work when dragged in, but HEIC is not guaranteed or advertised as a dependable input.

PDFs: any PDF that opens in a browser. The PDF tool focuses on merging and splitting; it does not currently render PDFs to images, but that is on the roadmap.

Audio: the picker accepts MP3, WAV, OGG, FLAC, M4A/AAC, and WebM audio, but input decoding depends on the browser's Web Audio support. Bundled encoders add output choices, not general input decoding.

Video: the picker accepts MP4, MOV, MKV, WebM, M4V, and browser-identified video files. FFmpeg handles several output paths, but codec and container compatibility still determines whether a particular file succeeds.

Images: JPG, PNG, WebP, QOI, and raw RGBA.

PDFs: a single merged PDF, or one PDF per page when splitting.

Audio: WAV, MP3, FLAC, M4A/AAC, WebM audio, and OGG. OGG uses browser Opus where available or FLAC in an OGG container as the bundled fallback.

Video: MP4 (H.264), WebM (VP9), MOV, MKV, and M4V depending on the browser's encoding support. WebM uses native browser recording; the others use bundled FFmpeg.

Re-encoding video is computationally heavy work. The browser has to decode every frame of the source, optionally resize it, then re-encode it with the chosen codec. A 1-minute 1080p clip can take anywhere from 20 seconds on a fast desktop CPU to several minutes on a phone.

WebM output is usually the fastest because it uses native browser recording APIs instead of WebAssembly FFmpeg. MP4, MOV, MKV, and M4V are slower because they use FFmpeg in software.

The local version uses the same FFmpeg WebAssembly engine inside the browser. It removes the website size check and network dependency, but it is not a native FFmpeg executable and should not be expected to encode faster.

Yes, for images. Drop multiple files into the image drop zone and they convert in sequence, each with its own download. For PDFs, you can also drop multiple files at once when using the "merge" action.

Video inputs are processed sequentially. Multiple audio conversions can start concurrently, so add long audio files one at a time to reduce memory pressure.

No. The conversion runs locally in your browser. The file is read from your device, processed in memory inside the browser tab, and the result is given back to you for download.

You can verify this yourself: open your browser's DevTools (F12), go to the Network tab, and run a conversion. You will see no outbound request that contains your file data.

No. Display ads are loaded by separate ad-network scripts that have no access to the data you drop into the converter. The ads run in their own sandbox provided by the browser. Your file never enters their world.

If you would rather not see ads at all, download the local version. It contains no ad scripts.

We do not currently use any user-tracking analytics. Our hosting provider keeps short-lived access logs (IP, user agent, requested URL, timestamp) for security and abuse prevention, the same as any web host. Those logs are not connected to your files in any way — they record that someone visited a page, nothing else.

The advertising cookies used by Google AdSense are described in detail on our privacy policy page, including how to opt out.

The web version needs its page and the engine for the selected tool. PDF and FFmpeg assets can load only when first used, so disconnecting immediately after opening the page may prevent a first conversion even though file processing itself is local.

For a truly offline-only experience, download the local version. It is a ZIP that you can unpack and run from any folder on your computer, no internet required after download.

A ZIP containing the converter and its local engines, with no executable advertising code or conversion-server dependency. Unzip it anywhere and open the included index.html in a current browser.

The local version has the same conversion features and removes the website's 30 MB check. Very large files can still fail because it remains a browser application.

Go to the download page and use the immediate download button. No signup, payment, ad view, or countdown is required.

Unzip the file. You will see an index.html file alongside the converter scripts. Double-click index.html, or right-click and "Open with" your preferred browser. The converter loads and works exactly like the web version, minus the ads.

On Windows, you may see a SmartScreen warning the first time. That is normal for any new file you have not run before; click "More info" then "Run anyway" once you have confirmed you trust the source.

Not on any schedule. The local ZIP is self-contained. When we ship significant improvements to the conversion code, we update the download. If you want the latest version, re-download the ZIP every few months or whenever you notice the website has new features.

No. There are no paid plans, no premium accounts, and no paywalled features. The website is supported by display ads served through Google AdSense; the local version is free and ad-free.

Ads help fund the project. Google may place ads automatically on monetized web pages. Ads must remain visually separate from converter controls and download actions.

If you would rather not see them, download the local version — it has no ad scripts at all.

Visit Google's Ads Settings to turn off personalization across Google services, or aboutads.info to opt out across many ad networks at once. You will still see ads, but they will not be tailored to your browsing history.

For users in the EEA, UK, or Switzerland, personalized advertising is not intended to be served unless consent has been gathered through a Google-certified Consent Management Platform configured in AdSense.

Ads are served by Google's ad network, not by us, so the destination is not something we control. If an ad sent you to something that looks like a scam (fake antivirus warnings, "your PC is infected" pages, fake software downloads), you can report it through the small information icon on the ad itself, or send us the details and we can flag it on our end too.

Use a current Chrome, Firefox, Safari, or Edge release. WebAssembly alone is not enough for every tool: Canvas, Web Audio, MediaRecorder, and codec support also vary by browser and operating system.

Older browsers will load the page but may not be able to run the heavier converters (video, audio re-encoding). Image and PDF tools have a better chance of working on older browsers because they use lighter APIs.

Yes, for images and PDFs especially. Audio works but is slower because mobile CPUs are less powerful. Video conversion is technically supported but can be slow and may stress device memory; for long video work, a laptop or desktop is a better fit.

Browser code runs inside a sandbox with restricted CPU usage and memory access. Native desktop apps have no such restrictions and can run multiple CPU cores in parallel without the same overhead. For occasional conversion this is fine; for heavy daily work, a desktop app or our local version (which still runs in a browser but skips network overhead) is faster.