Freeware - CRQL Anina Spectral Resonance Supression VST Plugin

https://crql.works/downloads/anina/

Free spectral resonance suppression

Just like most CRQL products, this plugin utilizes spectral processing. This gives ANINA a minimum of 256 bands of compression. While this introduces some latency (11ms on average), the trade-off for accuracy and speed is well-worth it in our opinion. Use lower blocksizes for a tighter feel, and higher blocksizes for better frequency resolution. Even when it seems like it's not processing, you may experience subtle pre-ringing and very slight changes in timbre and transients. The quirks of spectral processing.

Freeware - Tape Fiasco VST Plugin

https://www.erikssonjonas.com/tapefiasco

Tape Fiasco is a creative audio effect plugin that combines three distinct time-based effects: Stretch (granular time-stretching), Varispeed (tape-style speed manipulation), and Stutter (rhythmic slicing and repetition). Each effect can be used independently or in combination, with configurable signal routing between them. The plugin is designed for real-time performance and sound design, offering tempo-synced operation, envelope follower modulation, and extensive parameter control for each effect section.

Freeware - Softloop Harmonic Echo VST Plugin

https://softloopaudio.gumroad.com/l/harmonic-echo

This is a generative MIDI effect that transforms simple input into evolving, musical sequences. Instead of just repeating your notes, it climbs, falls, and harmonizes through the scale of your choice—acting like a creative co-pilot in real-time.

Freeware - Calgoheen cStop VST Plugin

https://github.com/calgoheen/cStop/releases

Tape stop start plugin.

Freeware - Sotto Spindown VST Plugin

https://sottovocedsp.com/products/sotto-spindown

Sotto Spindown is a plugin that recreates the sound of a vinyl record winding down. Instead of a fixed effect, you get full control: draw your own spindown curve and shape the slowdown exactly how you want it. Try a dramatic halt or gentle fade, the power is in your hands. If you’re after a custom vinyl-style slowdown, give it a spin for free!

Freeware - ChordBloom VST Plugin

https://www.pentacom.jp/pentacom/chordbloom/

ChordBloom is a creative plugin that makes discovering and performing chords feel intuitive and fun. Press keys in the lower octave (C2-B2) to shape the chord type, then explore rich voicings with a single touch from C3 upward. Whether you're sketching ideas, writing songs, or performing live, ChordBloom helps you find harmony—effortlessly.

Freeware - Ghost Note Audio Spectrum Thief VST Plugin

https://ghostnoteaudio.uk/products/spectrum-thief

Spectrum Thief is an EQ-matching plugin that can import and export impulse responses. Great for capturing the frequency response of speaker cabinets, or creating adjustment filters to tone-match your guitar tone (or even a full mix), to a reference sound. The plugin is FREE and requires no authentication or registration, so grab your copy!

Melody Mate

https://melody-mate-khaki.vercel.app/

Melody Mate MIDI Melody Generator website

Freeware - GATE12 VST Plugin

https://github.com/tiagolr/gate12

GATE-12 is a cross-platform envelope generator for gate/volume control inspired by plugins like GrossBeat and ShaperBox. It is the second version of GATE-1 rebuilt from scratch using the JUCE framework.

Freeware - Algoriffix Pitch Perfekt VST Plugin

https://www.algoriffix.com/

Pitch Perfekt is a vocal pitch correction plugin, which allows you to sing melodies into your mic and translate them to MIDI in real time. Load up your favorite synth or sampled instrument and use your voice as a MIDI controller or just capture your musical ideas on the spot.

Also paid Transkr converts polyphonic guitar to MIDI.

Freeware - XBox and PS MIDI Control VST Plugin

https://oceanswift.net/freebies/

Transform your XBox, 360, Playstation and Aimpad controller into a powerful, intuitive and fun midi controller. To use in Audio or Video applications.

Windows Only

Plenty of other synths and sample packs.

Google Experiment - Instrument Playground

https://artsandculture.google.com/experiment/8QFo2oQr2uT3pg

Cool web app for AI instrument samples.

Freeware - ab-reference VST Plugin

https://github.com/mannixsquared/ab-reference

A free plug-in which allows you to compare your mix against a reference track easily in your DAW

Freeware - ConvertWithMoss Utility

https://github.com/git-moss/ConvertWithMoss?tab=readme-ov-file

Converts multisamples from a source format (WAV, multisample, KMP, wavestate, NKI, SFZ, SoundFont 2) to a different destination format.

This tool converts multisamples in a specific source format to a different destination format. Furthermore, it can create multisample files from plain AIFF and WAV files. Additionally, the conversion process reads and writes metadata (name, category, creator, description and keywords) as well as envelopes and filter settings, if supported by the format. If the source format does not support metadata a guessing algorithm is applied based on the samples names.

Freeware - AP Mastering Compview VST Plugin

https://www.apmastering.com/compview/

Designed to inspect the gain reduction curvature of compressors

Requires a special test tone, supplied with the plugin

Open source

Diktatorial Suite AI Online Mastering

https://diktatorial.com/

Paid Product. Online AI Mastering with text prompt direction.

Freeware - Outobugi VST Plugins

https://outobugi.com/

Refire, Dynastia, Clamp, Wave, Extend, Dynastor, Termos, Dualcut, Toner

Freeware - Accusonus ERA Bundle VST Plugins

https://archive.org/details/accusonus-era-bundle-v-6.2.00

The ERA 6 Bundle Standard includes 11 easy-to-use plugins that help creators tackle all the audio issues they routinely face, literally in seconds. 

Designed for speed and fidelity, the ERA plugins help you get professional audio results with minimal effort, even if you've never edited audio before. 

The ERA 6 Bundle Standard includes the following products: 

[NEW] De-Breath. 

[NEW] Mouth De-Clicker. 

Voice AutoEQ. 

Voice Deepener. 

Audio Cleanup Assistant. 

Noise Remover. 

Reverb Remover. 

Voice Leveler. 

De-Clipper. 

De-Esser. 

Plosive Remover. 

Accusonus has been acquired by Meta and is now defunct. They're slowly being erased from the internet, but these plugins were made available for free prior to the vanishing. This has the latest versions for Mac and Windows (32 and 64-bit).

Freeware - SaschArt LoudnessMeterFree VST Plugin

https://vst.saschart.com/free_loudness_meter_audio_plugin_lufs_loudness_analyzer_loudnessmeter

SaschArt introducing an user friendly audio plugin designed for loudness (LUFS) analysis with a visual interface contain five measuring bars. This plugin make analyzing per each channel and show the difference of left-right for optimal stereo balancing. Achieve perfect loudness balance and professional-grade audio production with loudnessMeterFree.

ChordChord Generator

https://chordchord.com/generator

Free web-based chord generator and arrangement tool.