LAME MP3 Encoder is a useful and one of the best mp3 encoder and is available for free. You can use the LAME executable with RazorLAME interface or you can use the DLL with another software (AudioGrabber, CDEx etc). I prefer the combination CDEx or AudioGrabber + LAME DLL. In the archive are included both: exe and DLL.

Features:
* Many improvements in quality in speed over ISO reference software.
* MPEG1,2 and 2.5 layer III encoding.
* CBR (constant bitrate) and two types of variable bitrate, VBR and ABR.
* Encoding engine can be compiled as a shared library (Linux/UNIX), DLL or ACM codec (Windows).
* Free format encoding and decoding
* GPSYCHO: a GPL d psycho acoustic and noise shaping model.
* Powerfull and easy to use presets.
* Quality is comparable to FhG encoding engines and substantially better than most other encoders.
* Fast! Encodes faster than real time on a PII 266 at highest quality mode.
* MP3x: a GTK/X-Window MP3 frame analyzer for both .mp3 and unencoded audio files.

Whats New in version 3.98:
* Anton Sergunov: Frontend DirectShow: enabling LAME dshow filter to connect to "File Writer Filter".
* Rog rio Brito: Updates to the Debian Packaging
* Fixes to the abx tool for Unix systems (so that more people can evaluate LAMEs compression against the original files)
* Alexander Leidinger: explicitely link the math lib to the lame lib add switch to disable the use of the compaq optimized math lib

The license of this software is Freeware, you can free download and free use this audio converter software.