Convert FLV to MP4
Flash is gone; your videos don't have to be. Converted privately on your own machine.
Drop your video or audio here
or
MP4, MOV, WebM, MKV, AVI, MP3, WAV and more — any size, no upload
🔒 Files never leave your device — everything runs in your browser.
FLV was the container of internet video's first golden age — early YouTube rips, screen recordings, game clips, whole archives saved from sites that no longer exist. When Flash died in 2020, everyday players quietly dropped the format with it. The files still hold perfectly good video; they just need a modern wrapper. Converting to MP4 (H.264 + AAC) makes them playable on every phone, TV, and editor made this decade.
ConvertUno carries its own software decoder for the Flash-era codecs (H.263 variants, VP6, early H.264-in-FLV), so the conversion runs entirely on your device — no upload, no queue. Old FLVs are usually small, so most convert in well under a minute.
How it works
- Drop your file
Any common format, any size. Nothing is uploaded — the tool runs in your browser.
- Convert
Compatible files are repackaged instantly with zero quality loss; others are hardware-transcoded at high quality.
- Download
Your converted file is ready on your device — nothing to wait for, nothing to delete from a server.
Frequently asked questions
Why won't my FLV files play anymore?
Players dropped Flash-era formats after Adobe ended Flash in 2020. The video data inside your files is fine — it is the container and its old codecs that modern software refuses. Repackaging into MP4 solves it permanently.
Will the quality get worse?
The re-encode is set to a visually faithful quality level, and Flash-era video is low-resolution by today's standards, so the MP4 typically looks identical to the source at a similar or smaller size. Keep the FLV as your archive copy if it matters.
Can I convert FLV to MP3 instead?
Yes — pick MP3 as the output format and the audio track is extracted on its own, which is handy for music rips and voice recordings saved as FLV.
Is my file uploaded to a server?
No. ConvertUno runs entirely in your browser on your own device. Your file never leaves your computer or phone — there is no upload at all.
Is it really free, with no watermark?
Yes. Processing happens on your device, so serving you costs us almost nothing — no watermark, no account, no file-size limit, no daily quota.