Sourced from [webglstats.com].
WebGL 1
WEBGL_extension_pack1_1
- blend_minmax: 88%/96% (99% w/o ie+edge)
- debug_renderer_info: 100%/100%
- element_index_uint: 100%/93% (88% Chrome Android)
- instance_arrays: 99%/92% (86% Chrome Android)
- lose_context: 100%/100% w/o ie+edge
- standard_derivatives: 100%/100%
- vertex_array_object: 100%/100% w/o ie+edge
Maybes
- depth_texture: 90%/84%
- 96% w/o ie
- 71% android
- 100% iOS
- draw_buffer: 67%/1%
- Chrome Windows/macOS/Linux: 71%/95%/47%
- Chromium Linux: 79%
- Firefox Windows/macOS/Linux: 92%/99%/97%
- Exists on Firefox Android (percentage unknown)
- frag_depth: 87%/0%
- 92% w/o ie
- 100% Firefox Desktop
- 89% Chrome Desktop?
- 0% both Chrome Android and Safari iOS
- Exists on Firefox Android (percentage unknown)
- texture_filter_anisotropic: 99%/74% (only 52% Chrome Android)
- texture_float: 99%/75%
- texture_float_linear: 96%/60%
- texture_half_float: 93%/74%
- 99% w/o ie
- 53% Chrome Android
- texture_half_float_linear: 92%/73%
- 98% w/o ie
- 99% w/o ie+edge
- 51% Chrome Android
WebGL 2
WEBGL_extension_pack2_1?
Likely not enough common extensions to be worth it.
- color_buffer_float: 100%/84%
- disjoint_timer_query: 92%/86%
- texture_filter_anisotropic: 99%/45%
- texture_float_linear: 100%/40%