Changes

:The proprietary reference implementation, which Adobe stopped directly supporting at the end of 2020. The web plugin version relies on [[wikipedia:NPAPI|NPAPI/PPAPI]], an obsolete browser plugin system has been delisted from Adobe's website and also has a built-in kill-switch that for many years only stuck around specifically because of Flash Player; as Adobe was phasing out the pluginflipped in January 2021, so too was the plugin system gradually being dropped by all it's probably not much use even in browsers that still support NPAPI. However, the major browser vendors. The discontinued desktop player version is still available for download from the debug downloads section of Adobe's website, and Harman International is also [https://airsdk.harman.com/flashplayer maintaining an extended support version specifically for enterprise users].

:A C++ implementation that's designed specifically to provide drop-in FLOSS replacements for both the desktop and NPAPI versions of Flash Player. It claims to have 83% of the APIs overall SWF spec covered, as of August 2022. Lightspark historically focused on more recent versions of the Flash SWF spec that weren't supported by Gnash, hence why Lightspark could (and still can) use Gnash as an automatic fallback if both are installed simultaneously.

:A desktop-only C++ implementation that went inactive in 2017, with the most recent stable release dating back to 2012. Probably not much reason to use it over newer versions of Lightspark, which seem to have mostly (if not entirely) superseded Gnashfor compatibility.

:Another very early effort to replicate create an non-proprietary replacement for Flash Player's NPAPI plugin in open-source. Actually pretty advanced for 2008-09, but it hasn't been active since.

;''Common aspects'':''Pretty much all of the implementations listed here are specifically designed to be used as [[wikipedia:Polyfill (programming)|polyfills]] by webmasters who want to keep their Flash-based sites going despite the forced obsolescence of Adobe's in-browser Flash plugin. They are therefore really largely not intended for personal use, although it's usually not impossibleand some of them even have official demo pages that you can use to load whatever SWF file you want.''

:A proprietary software package designed to make the Harman version of Flash Player usable in modern web browsers by running it inside CheerpX, a payware x86 emulator in WebAssembly. No-one on this wiki has had the chance to properly evaluate it, but we'd expect reference-level accuracy at the cost of woeful performance. That being said, CheerpX apparently has an alternate mode of operation that offloads most of the emulation and processing work to a server app, at which point the in-browser part is effectively just a streaming client.

:An HTML5 implementation developed Developed by the Away Foundation. Sometimes works better than , this is arguably the most direct alternative to Ruffle, and it sometimes ''does'' work better depending on the specific Flash SWF file you're trying to run.

:An inactive, closed-source C++-to-HTML5 WebAssembly implementation that technically hasn't been made available to outside users, although there are a few sites where you can use it. It was considered the most accurate of the unofficial Flash players as of late 2021, although Ruffle and AwayFL have since caught up significantly.

:An open-core HTML5 implementation that uses a dynamic recompiler. The source-available "Free" version supports limited features, such as AS1, AS2 and ZLIB compression, whereas the payware "Production" version is better suited to newer Flash files using such features as AS3 and LZMA compression. Built on more traditional JavaScript code, so it pretty much always performs worse than the WebAssembly-based options, sometimes noticeably so.

:A relatively very early HTML5 implementation. Developed , developed rather actively under Mozilla sponsorship between 2012 and 2016, but ultimately abandoned before it could reach a usable beta state.