Free
Slowed + Reverb
& Nightcore Converter

From your own files, yes: free, unlimited, no watermark and no signup, in MP3, WAV and FLAC. Importing from a YouTube link needs paid access — €6.99 for seven days or €19.99 for a year, a one-off payment with no subscription — because that extraction costs server resources and constant upkeep.

It's simple: import your music, then increase the speed between 1.10x and 1.25x. The algorithm will automatically adjust the pitch for that characteristic high-pitched Nightcore voice.

Absolutely. We use Web Audio API technology which processes sound directly in your browser. Your files are never uploaded to a server, ensuring total privacy.

Yes, our tool is mobile-optimized. You can create slowed + reverb versions directly from Safari (iOS) or Chrome (Android) and save the audio file to your documents.

ConvertiSlowed accepts MP3, WAV, OGG, FLAC and M4A formats. You can import any common audio file from your device (phone, computer, tablet).

Speed Up only accelerates the tempo without changing the vocal pitch. Nightcore speeds up both the tempo AND raises the pitch, giving that characteristic high-pitched voice typical of anime and gaming culture.

There is no strict server-side limit since all processing is local (in your browser). Performance depends on your device. For very large files (>50 MB), a computer with at least 4 GB of RAM is recommended.

Yes, the reverb slider is fully independent of speed and pitch. You can adjust it from 0% (no effect) to 100% (maximum reverb) depending on the desired result.

Once the page is loaded in your browser, audio processing works entirely locally without an internet connection. You only need internet for the initial page load.

Slowed only reduces the tempo without changing the pitch. The Slowed + Reverb version adds spatial reverberation that creates an enveloping atmosphere. Nightcore does the opposite: it speeds up the tempo and raises the pitch, creating an energetic, high-pitched effect. Speed Up is a modern version of Nightcore applied to more varied genres. Each effect transforms the mood of a track in a radically different way.

ConvertiSlowed lets you technically process any audio file, but the legality of commercial use depends on the rights for the source track. For commercial use (selling, YouTube/TikTok monetization), you must own the rights to the original track or use royalty-free and Creative Commons music. Contacting independent artists directly is often fruitful for obtaining permission.

ConvertiSlowed uses advanced processing algorithms (Web Audio API) that preserve sound quality during tempo changes. Unlike simple methods that create digital artifacts, our engine maintains vocal clarity and bass dynamics. For maximum quality, export as WAV or FLAC rather than MP3 — these uncompressed formats retain 100% of audio data.

ConvertiSlowed accepts audio files up to 100 MB for direct import from your device. This limit covers the vast majority of use cases: a 10-minute MP3 at 320 kbps weighs about 22 MB, and a 10-minute WAV about 100 MB. If your file is larger, we recommend converting it to MP3 before importing, or splitting it into multiple parts.

ConvertiSlowed's Bass Boost amplifies low frequencies between 60 and 200 Hz using a shelf boost filter. At moderate levels (8-15%), it warms the sound without saturation. Above 25%, it can create audible distortion on tracks that are already heavily saturated in the bass range. For Slowed + Reverb effects, a Bass Boost of 10-15% is generally optimal.

ConvertiSlowed runs entirely in your browser via the Web Audio API — all audio processing happens locally on your device. However, an internet connection is needed to load the application itself the first time. Once the page is loaded, you can continue using the tool even if your connection becomes unstable, as no data is sent to our servers during processing.

Yes, ConvertiSlowed allows you to combine multiple effects simultaneously: you can adjust speed, apply reverb, and boost bass in one operation. It's precisely the Slowed + Reverb + Bass Boost combination that creates the characteristic lo-fi sound so widely appreciated. The real-time preview lets you hear the result immediately before exporting.

ConvertiSlowed uses the Web Audio API, a standard supported by all modern browsers (Chrome, Firefox, Safari, Edge). Results are nearly identical across browsers. For best performance, Chrome and Edge offer the most optimized implementations of the Web Audio API. On iOS, Safari is recommended for smooth processing of large files.

For TikTok and Instagram, export your creation as MP3 320 kbps. These platforms recompress audio upon upload, so starting with a high-quality file better preserves the final result. For TikTok, identify the 15-60 most compelling seconds of your slowed track to create your clip. On Instagram Reels, you can also import a WAV file directly for better quality before compression.

No limit on volume, in either mode. Local file mode is entirely free, with no registration and no subscription: import as many files as you like. YouTube mode requires paid access — €6.99 for seven days or €19.99 for a year, a one-off payment with no renewal — because extracting from YouTube costs server resources and demands constant upkeep against blocking. Once your access is active, it has no limit either.