The work is executed in the page through browser workers, WebAssembly, Web Audio, or WebGPU as stated.
FADE / AVAILABLE NOW
Fade In / Fade Out
Shape clean starts and endings. Set separate fade-in and fade-out times, choose musical curve shapes, preview the envelope, and export locally.
FADE / envelope workbenchSample-accurate fades in a local worker
FADE IN1.00sS-curveCENTER GAINPREVIEWNo file loadedFADE OUT3.00sEqual power
Original and faded previews appear here after you choose a file.
GUIDE / fade audio online
What are fade-in and fade-out in audio?
An audio fade changes gain gradually instead of starting or stopping at full level. A fade-in rises from silence at the beginning; a fade-out moves toward silence at the ending. SoundTools applies a sample-by-sample envelope to every linked channel in a local Web Worker, so the rendered WAV or MP3 contains the audible change and not merely a player-volume setting.
RELATED USES
- fade in audio online
- fade out audio online
- MP3 fade out
- add fade to audio
- audio fade editor
FIELD NOTES / 01
A real local processor, not a decorative upload box
Sample-accurate linked-channel gain envelope worker runs after you choose a source and explicitly start the operation. The audio samples remain in browser memory; SoundTools does not send the selected media to an application endpoint.
Set fade-in and fade-out lengths independently, choose linear, equal-power, S-curve, or exponential shapes for each edge, inspect the envelope over the waveform, then render and compare the original with the faded result. Results remain available for preview and download only in the current tab. Closing or refreshing the page releases those temporary objects.
REFERENCE / MODE CHOICE
Linear vs equal-power vs S-curve vs exponential fades
Every curve reaches the same endpoints; the difference is how quickly perceived level changes between them. Preview the source material because speech, music, and ambience respond differently.
| Method | Best for | What it measures | Important limit |
|---|---|---|---|
| S-curve | Natural all-purpose intros and endings | Slow edges with a quicker middle transition | Can feel too gentle for a very short edit boundary |
| Equal power | Music and sustained material | Sine-shaped gain intended to feel even through the transition | It rises faster than linear near the silent edge |
| Linear | Short utility fades and click reduction | Constant sample-gain change over time | Human loudness perception may make it sound less even |
| Exponential | Long, dramatic fade-ins or fade-outs | More of the transition stays close to silence | Can make a short fade feel abrupt near its loud edge |
PROCESS / THREE STEPS
How to use fade in / fade out
- 01
Choose the local source
Open a compatible file in the dedicated workbench at the top of this page. The browser validates and decodes it without an upload step.
- 02
Set the useful controls
Set fade-in and fade-out lengths independently, choose linear, equal-power, S-curve, or exponential shapes for each edge, inspect the envelope over the waveform, then render and compare the original with the faded result.
- 03
Process, check, and export
Run the local processor, inspect the status and preview, then save Faded WAV · 192 kbps MP3 when the result is ready.
SIGNAL NOTES / VERIFIED BEHAVIOR
What this tool actually does
Clear limits are part of a useful tool. These values describe the processor currently running in this page.
Runtime and model assets may be downloaded, but the selected file is not attached to those requests.
The dedicated workbench exposes only formats it can actually produce in the current browser.
USE CASES / 02
Useful reasons to open fade in / fade out
- Podcast edits and voice clips
Hide abrupt cuts or tiny boundary clicks with short, controlled fades before a handoff.
- Music intros and endings
Bring in a track gradually or create a deliberate ending without opening a full multi-track editor.
- Loops, ambience, and video audio
Soften the entrance and exit of background beds, samples, and sound effects before placing them in a timeline.
QUESTIONS / PRACTICAL ANSWERS
Questions about this tool
Answers based on the current browser processor—not promises about a future version.
01Is my audio uploaded for processing?
No. Audio samples stay in browser memory. The page may download a codec or model asset, but it does not send the selected file with that request.
02Why can the first run take longer?
This tool uses Sample-accurate linked-channel gain envelope worker. A browser may need to download and initialize that runtime before the first operation; later runs can reuse cached assets.
03Can I preview the result before saving?
Yes. Audio-producing tools expose local result players, while analysis and transcription tools show their detected data before download.
04What happens when the browser is unsupported?
The workbench reports the missing capability instead of uploading the media or pretending that processing is still running.
05Do I need an account or install?
No. The tool opens directly in a compatible browser, requires no SoundTools account, and creates its temporary working state on the current device.
06Which fade curve should I choose?
S-curve is a gentle general-purpose choice, equal-power feels musical, linear is direct for short utility fades, and exponential stays quieter longer for a more dramatic entrance or ending.
07Can I apply only a fade-in or only a fade-out?
Yes. Set the unused edge to 0.00 seconds. The worker leaves that edge at full gain and renders only the requested fade.
08What happens if the fade-in and fade-out overlap?
Both envelopes remain active and the lower gain is used at each sample. The result stays bounded, but the middle may never reach full level; the blue preview line shows that before rendering.