Why Do This in Your Browser?
Adding a fade is the single most ubiquitous audio edit and somehow still requires opening a DAW for most people. The math is trivial — multiply samples by a ramp curve — and yet the workflow's friction is real: download a DAW, import the file, draw the fade envelope, render. For a 3-second fade-in on a podcast intro, the friction is the whole job.
FFmpeg's `afade` filter applies any of 17 fade curve shapes in a single pass. The browser tool exposes the four that matter most: linear (constant slope), exponential (slow start, fast end), logarithmic (fast start, slow end), and quarter-sine (smooth-sounding default). The fade applies to the input and exports in seconds.
How It Works
Drop an audio file. The tool displays the waveform with two fade-zone overlays: one at the start (fade-in), one at the end (fade-out). Adjust each independently — duration (0–30 seconds) and curve shape (linear / log / exponential / quarter-sine). Enable only one or both. Preview the result instantly (Web Audio scrub) before final export.
On export, FFmpeg.wasm applies the chosen curves via `afade=t=in:start_time=0:duration=N:curve=X,afade=t=out:start_time=T:duration=N:curve=X` and writes the output. Source format is preserved by default; you can override to a different format if you want format conversion in the same pass.
Tip: For trimming the audio before adding fades, use the Audio Trimmer first — fades sound better on cleanly-cut edges. After fading, run a final loudness pass with the Audio Normalizer for distribution-ready output. For pitch correction on the faded clip (e.g., transposing a music intro to a different key), the Audio Pitch Shifter shifts up to ±12 semitones without changing duration.
Common Use Cases
How We Compare
Honest read on free, paid, and self-hosted options for this kind of job: