There are few compressors more coveted than the legendary LA-2A compressor by Teletronix.
The electro-optical compressor is famous for its gentle transparent compression, making it the perfect choice for pristine vocal levelling, bass and drums, or anything that requires gentle dynamic reduction or additional warmth.
Free plugin versions are rare, so this is a sweet find: the AdHd Leveling Tool, a free download (or, more specifically, donationware) from the cool cats at AdHd.
Compatible with both Windows and Mac the AdHd aims to provide all that sweet, sweet Teletronix mojo to your tracks without the eye-watering price.
Have at it!