Time to Stable

For a given set of browsers, what APIs are in all of them and how many days it take for the API to land in the first browser to the last.

Example Comparisons
Browsers
Features

Summary

A count of the number of APIs that landed in A first and B last.
Last in FirefoxLast in Safari
First in Firefox 52
First in Safari 9

Average time for an API to become available across Firefox and Safari

61 APIs took an average of 316.38 days to become available to use.

API breakdown:

Average time to landing by year of first landing

If a feature landed in the earliest browser in 20XX it took Y days on average to become available in the last browser (when considering Firefox and Safari). TTA (time to available).
WebAssembly APIsWebAssembly TTA
2017 28196.00
2018 9835.00
2020 6394.67
2021 9199.11
2023 4343.25
2024 2181.00
2025 3133.67

The Tortoise and the Hare

There is a natural tension on the web with respect to browser engines. Every engine has their own set of priorities which define the level of investment that they choose to make and on which areas they choose to make it.

A developer naturally wants their experiences to be available to the widest audience possible and these differing priorities create an unevenness on the platform (a lumpiness) making it harder for developers to build experiences that work everywhere.

This section highlights where browsers are pushing and pulling on the platform.

Sprinters

This table is designed to show which browsers are pushing on the platform the most.

Adding features to quickly is not always desired because developers are unlikely to adopt those features in their sites or apps.

For a given year, if a feature landed in Browser X first, how many days it take on average to be available in Firefox and Safari. TTA (time to available).
Year WebAssemblyWebAssembly TTA
2017
  Firefox 28196.00
2018
  Firefox 9835.00
2020
  Firefox 5454.00
  Safari 198.00
2021
  Safari 8141.00
  Firefox 1664.00
2023
  Firefox 4343.25
2024
  Firefox 2181.00
2025
  Firefox 3133.67

Plodders

This table is designed to show which browsers are pulling on the platform the most.

For a feature that first landed in year X, how many days did it take on average for the last browser to catch up across Firefox and Safari. TTA (time to available).
Year WebAssembly countWebAssembly TTA
2017
  Safari 28196.00
2018
  Safari 9835.00
2020
  Safari 5454.00
  Firefox 198.00
2021
  Firefox 8141.00
  Safari 1664.00
2023
  Safari 4343.25
2024
  Safari 2181.00
2025
  Safari 3133.67

Stable APIs

Below is a list of features that are in Firefox and Safari

Raw Data

Quick Links:

WebAssembly Data

API First Browser Date Last Browser Date Days Notes
webassembly.BigInt-to-i64-integration 📋Firefox6/30/2020 Safari4/26/2021300
webassembly.api 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.CompileError 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.CompileError.CompileError 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Exception 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.api.Exception.Exception 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.api.Exception.Exception.options_parameter_traceStack Safari12/13/2021 Firefox5/3/2022141
webassembly.api.Exception.getArg 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.api.Exception.is 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.api.Global 📋Firefox9/5/2018 Safari3/24/2020566
webassembly.api.Global.Global 📋Firefox9/5/2018 Safari3/24/2020566
Chrome: Constructing a Global with a value of v128 produces a TypeError.Chrome Android: Constructing a Global with a value of v128 produces a TypeError.Deno: Constructing a Global with a value of v128 produces a TypeError.Edge: Constructing a Global with a value of v128 produces a TypeError.Node.js: Constructing a Global with a value of v128 produces a TypeError.Quest Browser: Constructing a Global with a value of v128 produces a TypeError.Opera: Constructing a Global with a value of v128 produces a TypeError.Opera Android: Constructing a Global with a value of v128 produces a TypeError.Samsung Internet: Constructing a Global with a value of v128 produces a TypeError.WebView Android: Constructing a Global with a value of v128 produces a TypeError.
webassembly.api.Global.value 📋Firefox9/5/2018 Safari3/24/2020566
webassembly.api.Global.valueOf 📋Firefox9/5/2018 Safari3/24/2020566
webassembly.api.Instance 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Instance.Instance 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Instance.exports 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.JSTag_static 📋Firefox10/1/2024 Safari3/31/2025181
webassembly.api.LinkError 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.LinkError.LinkError 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Memory 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Memory.Memory 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Memory.Memory.shared 📋Firefox6/30/2020 Safari12/13/2021531
Safari: Shared WebAssembly.Memory is gated behind COOP/COEP. For more detail, read Making your website "cross-origin isolated" using COOP and COEP.Safari on iOS: Shared WebAssembly.Memory is gated behind COOP/COEP. For more detail, read Making your website "cross-origin isolated" using COOP and COEP.WebView on iOS: Shared WebAssembly.Memory is gated behind COOP/COEP. For more detail, read Making your website "cross-origin isolated" using COOP and COEP.
webassembly.api.Memory.buffer 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Memory.grow 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Memory.toFixedLengthBuffer 📋Firefox11/11/2025 Safari12/12/202531
webassembly.api.Memory.toResizableBuffer 📋Firefox11/11/2025 Safari12/12/202531
webassembly.api.Module 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Module.Module 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Module.customSections_static 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Module.exports_static 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Module.imports_static 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.RuntimeError 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.RuntimeError.RuntimeError 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Table 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Table.Table 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Table.get 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Table.grow 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Table.length 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Table.set 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.Tag 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.api.Tag.Tag 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.api.compileStreaming_static 📋Firefox1/23/2018 Safari9/20/20211336
webassembly.api.compile_static 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.instantiateStreaming_static 📋Firefox1/23/2018 Safari9/20/20211336
webassembly.api.instantiate_static 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.api.validate_static 📋Firefox3/7/2017 Safari9/19/2017196
webassembly.bulk-memory-operations 📋Firefox6/30/2020 Safari10/25/2021482
webassembly.exception-handling 📋Safari12/13/2021 Firefox5/3/2022141
webassembly.exceptionsFinal 📋Firefox10/1/2024 Safari3/31/2025181
webassembly.extended-constant-expressions 📋Firefox4/11/2023 Safari3/5/2024329
webassembly.fixed-width-SIMD 📋Firefox6/1/2021 Safari3/27/2023664
webassembly.garbage-collection 📋Firefox11/21/2023 Safari12/11/2024386
webassembly.jsStringBuiltins 📋Firefox1/7/2025 Safari12/12/2025339
webassembly.multi-value 📋Safari3/24/2020 Firefox6/30/202098
webassembly.mutable-globals 📋Firefox9/5/2018 Safari3/24/2020566
webassembly.non-trapping-float-to-int-conversions 📋Firefox12/11/2018 Safari10/25/20211049
webassembly.reference-types 📋Firefox7/28/2020 Safari10/25/2021454
webassembly.sign-extension-operations 📋Firefox9/5/2018 Safari4/26/2021964
webassembly.tail-calls 📋Firefox12/19/2023 Safari12/11/2024358
webassembly.threads-and-atomics 📋Firefox7/28/2020 Safari12/13/2021503
webassembly.typedFunctionReferences 📋Firefox11/21/2023 Safari9/16/2024300