What Is an Audio Joiner?
An audio joiner (also called an audio merger, combiner, or concatenator) is a tool that takes multiple separate audio files and stitches them end-to-end into a single continuous audio file. Unlike a playlist, the output is one file containing all the audio in sequence — compatible with any media player, podcast platform, or audio editor without requiring the individual source files.
This online audio joiner processes everything in your browser using FFmpeg compiled to WebAssembly. There are no server uploads, no account requirements, and no file size restrictions beyond available browser memory. Mixing formats is fully supported — you can join an MP3, a WAV, and an OGG file into a single M4A output in one operation.
How to Join Audio Files
Upload your audio files
Drag and drop multiple audio files onto the upload area, or click to browse. You can add MP3, WAV, OGG, M4A, AAC, FLAC, and even video files (MP4, MOV) to extract their audio track.
Reorder tracks
Drag the grip handle on the left of any track card to reorder it, or use the up/down arrow buttons. The timeline strip at the top updates in real time to preview the running order and proportional duration of each clip.
Configure per-track options
Click the ⚙ settings icon on any track to set a silence gap before it, a fade in and fade out duration, and a trim-start offset (to skip an intro or countdown). Each track can have independent settings.
Set output options
Choose an output format (MP3, WAV, OGG, M4A), set the crossfade duration between tracks if you want smooth blending, and type your preferred output filename.
Join and download
Click Join Tracks. FFmpeg processes all files locally in your browser. When done, click Download to save your merged audio file.
Common Uses for Audio Joining
Podcast production
Combine intro music, interview segments, ad breaks, and outro music into a single ready-to-publish episode file.
Audiobook creation
Merge individually recorded chapters into a complete audiobook file, adding silence between chapters for natural pacing.
Music compilation
Create mixtapes or DJ sets by joining songs in a chosen order, with crossfade transitions between tracks for a seamless listening experience.
E-learning content
Assemble recorded lecture segments, narrated slide audio, and quiz sections into one cohesive learning module audio track.
Presentation voiceover
Join separately recorded narration segments for each slide section into one synchronized voiceover file.
Sound design
Combine ambience tracks, foley recordings, and dialogue clips into a continuous audio bed for film, video games, or theatre.
What Is Crossfade?
Crossfade is an audio transition technique where the end of one track gradually fades out at the same time as the beginning of the next track fades in, so both tracks overlap briefly and blend together. The result is a smooth, seamless transition rather than an abrupt cut. Crossfade is standard in DJ mixes, radio broadcasting, music streaming apps, and podcast intros where a jarring hard cut between two clips would feel unpolished.
In this tool, crossfade duration is set globally and applied between every pair of tracks in the join. A duration of 1–2 seconds is subtle and professional; 4–8 seconds creates a long, immersive blend more typical of ambient music or meditation content.
Frequently Asked Questions
Technical note: Simple joins (no effects, no crossfade) use FFmpeg's concat demuxer — the fastest method, with minimal processing overhead. When per-track fades, silence gaps, trim offsets, or crossfade are enabled, the tool switches to FFmpeg's filter_complex pipeline, which resamples all inputs to 44,100 Hz stereo PCM before processing. The first join in a session loads the ~30 MB FFmpeg WASM binary; this is cached by the browser for subsequent uses.