Free Boomerang Maker

Worked example

Add a 1920×1080 clip called clip.mp4. The encoder starts loading as soon as the file lands, and "Encoder ready" appears when it has. Set "Start at" to 3 seconds and leave "Segment length" at its default of 2 seconds. Everything else is at its default: "Normal" speed, "1×" bounces, MP4, "Original" shape, "Silent" and "Full" size. The page says "Result: 1280×720 px, about 4.0 seconds long", because the longer side is held to 1280 px, and under the button "Estimated time: about 20 seconds." Press "Make boomerang". When it finishes you see "Boomerang ready" with the file size, a looping preview and a download button, and the file is named clip_boomerang.mp4. Pick "Draft (fast)" instead and the result becomes 480×270 px, and the estimate drops to "Should take under 10 seconds."

Which settings to use, and the limits

• Keep the segment short. "Segment length" runs from 0.5 to 5 seconds in 0.5 second steps and starts at 2. "Start at" moves in 0.1 second steps, from 0 to half a second before the end of the clip. The cap exists because reversing holds every frame in memory: the tool's own estimate is about 207 MB for 5 seconds at 1280×720 and 30 fps, before the input and encoder are counted. On a phone the longest segment is 3 seconds. "Loop segment preview" plays the segment forward and back in the page. It can look choppy, but the exported file is smooth.
• Choose MP4, GIF or WebM for where it will be shown. MP4 is H.264 with AAC sound at 128 kbps if you keep sound. WebM is VP8 with Opus sound at 96 kbps. GIF has no sound, is held to 480 px on the longer side at 15 fps, and loops by itself; the page notes that an MP4 plays once in WhatsApp, Discord, Slack and Telegram. "Repeat" (1×, 3×, 5×, 10×) is for MP4 and WebM only and copies the finished loop without re-encoding. On a computer MP4 and WebM go up to 1280 px at 30 fps; on a phone, 640 px at 24 fps.
• Crop to a post shape with "Shape". "Shape" offers "Original", 9:16, 1:1 and 16:9. The crop is centred, never enlarges the picture, and sizes are rounded down to even numbers. A 1920×1080 clip becomes 606×1080 at 9:16, 1080×1080 at 1:1, and 1280×720 at 16:9 after the 1280 px cap. Tick "Show the cropped area on the preview" to see the frame on the video. The "Result:" line updates as you change options.
• Shape the loop with speed and bounces. "Speed" has "0.5× slow-mo", "Normal" and "2× snappy". "Bounces" of "1×" plays forward then back once; "2×" plays forward, back, forward, back. The length of the result is segment ÷ speed × 2 × bounces × repeat. So a 2 second segment at "0.5× slow-mo" with "2×" bounces gives "about 16.0 seconds long" in the "Result:" line. A GIF ignores "Repeat" because it loops by itself.
• Decide about sound first. "Sound" is "Silent" by default, the classic boomerang look. "Keep sound" plays the clip's audio forward, then reversed, in step with the picture and at the chosen speed. The control is not offered for GIF. If the clip has no sound track, the page says "This clip has no sound track, so the result is silent." and still makes the file.
• Try "Draft (fast)", then render "Full". "Size" is "Full" or "Draft (fast)". Draft holds the longer side to 480 px and 24 fps (a GIF to 320 px and 12 fps), so a trial finishes sooner. Under the button the page estimates the time, for example "Should take under 10 seconds." or "Estimated time: about 20 seconds.", and after your first render it re-estimates from the speed it measured. Changing any setting discards the finished result, so press "Make boomerang" again.

Common problems and how to fix them

It says "This file changed or moved after you picked it — please choose it again."

A picked video is a reference to the file on disk, not a copy, and the encoder reads it while it works. If the file was moved, renamed, deleted or saved over after you picked it, that read fails. The tool drops the clip and shows the drop zone again, so add the file from where it is now, and keep it in place until the download has finished.

It says "Failed to load the encoder. Check your internet connection and try again."

The encoder is a download of about 31 MB that starts as soon as you add a clip. The page shows "Loading encoder…", then "Encoder ready". The download is stopped if no data arrives for 20 seconds, and it is checked for the right size and checksum when it ends; either failure gives this message. A dropped connection resumes instead of starting over, and a finished download is stored in the browser for next time. Wait for "Encoder ready", then press "Make boomerang" again on a steadier connection.

It says "The browser ran out of memory processing this file — it's too large for this device. Try a shorter clip, a smaller file, or a desktop computer."

Reversing holds every frame of the segment in memory at once, which is why phones are held to 3 seconds and 640 px. Shorten "Segment length", choose "Draft (fast)", or pick GIF, which is held to 480 px. A smaller source file helps too. On some Android phones the tab has been seen to close with no message at all when memory ran out.

It says "This file is 2.6 GB, which is too large to process in your browser on this device (limit ~2 GB). Try a smaller file or trim a shorter clip first."

The numbers are your file and your device's limit: about 2 GB on a normal computer, 1 GB on a computer that reports 4 GB of memory or less, and 400 MB on a phone. The check runs when you add the file, so nothing has been processed. The tool copies the whole file into the encoder even though it uses only a few seconds, so a long source counts in full. Cut it down in a video trimmer first.

It says "This conversion failed — the format or codec may not be supported for this input. Try a different source file."

The encoder could not read or write the clip as asked. Re-save the video as MP4 (H.264) in the app that made it and add that copy. If the page shows a technical line of English instead, that is the encoder's own error text, shown when the error matches none of the known kinds. Try the same fix with a shorter segment.

How it compares

An app that films and loops a clip in one step is quicker for a new shot. This tool starts from a video you already have and lets you choose the part, the speed, the number of bounces, a crop and the file type. It does not record, stabilise, filter or add text. It makes one forward-and-back loop from one segment of at most 5 seconds (3 on a phone), and the output is held to 1280 px on the longer side (640 px on a phone), so it is not a way to edit high-resolution masters. In exchange nothing needs installing and the video is processed in your browser, not uploaded.