bfxr
Flash + AIR sound effects generator. Based on Sfxr.
...It offers an interactive GUI through which you can tweak many parameters (oscillators, envelopes, filters, etc.) to sculpt custom sound effects; you can preview in real time, export, and iterate. The project includes libraries, HTML templates, and both ActionScript and JavaScript code. It has been well-received (over a thousand stars), but as of 2025, it has been superseded by a newer version called bfxr2, which is a JavaScript reworking of the original.