- [OnlineToneGenerator.com](https://www.online-tone-generator.com/) offers various types of waveforms, frequencies, and controls, including the option to set custom frequencies.
- [Tone-Generator.io](https://tone-generator.io/) provides similar features with different waveform options and additional controls such as amplitude and phase adjustment.
- [WebAudioTools](https://webaudio.prototyping.bbc.co.uk/tools/sine-wave-test-tone/) has a straightforward sine wave tone generator with adjustable frequency and volume.
- [AudioCheck.net](https://www.audiocheck.net/testtones_frequencygenerator.php) includes multiple presets for specific frequencies based on tuning standards and audio testing scenarios.
- [Synth Simulator](https://synthesizers.com/en/tone-generator.html) features a virtual synthesizer interface with options for different waveforms, envelopes, and other sound shaping parameters.
These tone generators may serve various purposes such as testing audio equipment, composing music, calibrating instruments, or simply experimenting with sound and frequency. Please note that the sound quality and flexibility of features may vary, and some websites may display advertisements.