Brass Pawn compared with 30 chess apps, engines and workflows.

How the five types of chess software divide the work

No single chess program covers tournament pairing, ten-million-game PGN trees and offline mobile coaching equally well. Start by matching the tool class to the job.

Architectural comparison of Brass Pawn against the main categories of chess software
Software categoryCore jobOffline engine & puzzlesTypical pricingWhere Brass Pawn differs
Brass Pawn (iPhone, iPad, Mac)Daily tactics, positional judgement, endgame conversion & coached engine playYes — Stockfish 18 & Reckless 0.10 bundled locally with 14,351 puzzlesFree unlimited play + 5/day training; Pro $3.99/mo or $39.99 onceAGPLv3 source, win-probability move grading, zero ads, zero chat
Online chess servers (Chess.com, Lichess)24/7 global matchmaking, arenas, clubs, streamer events & studiesPartial mobile caching; server-first ratings, social feeds & cloud analysisFree open-source (Lichess) or multi-tier freemium subscriptions (Chess.com)Trades massive global matchmaking pools for quiet offline training & Game Center play
Course & repertoire platforms (Chessable, Chess King)Memorising opening trees or buying standalone topic workbooksVaries by offline course sync; account requiredPer-course purchases plus optional monthly/annual membershipsDeliberately omits opening repertoire memorisation; unifies 8 modes under one roof
Desktop databases & UCI GUIs (ChessBase, HIARCS, En Croissant)Multi-million-game PGN search, opponent prep & deep engine treesYes on desktop once engines, books & databases are configuredFree open-source GUIs to $200+ desktop database packagesShips a curated 900-game decisive Watch library ready on iPhone, iPad & Mac with zero setup
Cloud AI coaches & casual 3D apps (Dr. Wolf, Noctie, Arcade)Conversational beginner hints, cloud human-like bots or casual 3D playCloud bots require internet; casual 3D apps vary and often carry adsRecurring SaaS/Arcade subscriptions or ad-supported virtual currenciesRuns deterministic position-feature coaching locally on device with no ad SDKs

Browse comparisons by category

30 comparisons shown

Online servers & analytics

Brass Pawn vs Chess.com

Compare Brass Pawn and Chess.com across offline Stockfish 18 coaching, puzzle limits, ad-free play, privacy and $39.99 one-off Pro vs recurring memberships.

Free play + 5/day drills; Pro $3.99/mo or $39.99 once vs Gold/Platinum/Diamond

Online servers & analytics

Brass Pawn vs Lichess

Compare Brass Pawn and Lichess: native iPhone, iPad and Mac coached sparring, 2D/3D boards and curated Watch games vs free global arenas and studies.

Free play + $3.99/mo or $39.99 Pro vs $0 free forever (optional patron)

Courses, coaches & AI trainers

Brass Pawn vs Chessable

Compare Brass Pawn and Chessable: interactive Stockfish 18 sparring, tactics and endgame conversion vs spaced-repetition opening repertoire courses.

Free play + $3.99/mo or $39.99 once vs individual course fees + Chessable Pro

Courses, coaches & AI trainers

Brass Pawn vs Dr. Wolf

Compare Brass Pawn and Learn Chess with Dr. Wolf across Stockfish 18 strength range, 14,351 tactics puzzles, offline privacy and one-off vs subscription cost.

Unlimited free coached play + $3.99/mo or $39.99 once vs recurring subscription

Courses, coaches & AI trainers

Brass Pawn vs Magnus Trainer

Compare Brass Pawn and Play Magnus / Magnus Trainer: classical chess positions, Stockfish 18 + Reckless and 900 master games vs arcade mini-games.

Free play + $3.99/mo or $39.99 once vs subscription membership

Engines, GUIs & PGN databases

Brass Pawn vs Shredder Chess

Compare Brass Pawn and Shredder Chess on iPhone, iPad and Mac: Stockfish 18 + Reckless, 14,351 tactics, win-probability coaching and Game Center play.

Free download & unlimited play (Pro $3.99/mo or $39.99) vs paid upfront app + desktop licenses

Online servers & analytics

Brass Pawn vs Aimchess

Compare Brass Pawn and Aimchess: private offline Apple chess training and coached engine play vs cloud scouting reports imported from online accounts.

Free play + $3.99/mo or $39.99 once vs recurring cloud analytics subscription

Online servers & analytics

Brass Pawn vs Chess Tempo

Compare Brass Pawn and Chess Tempo across native iPhone/iPad/Mac UX, offline Stockfish 18 coaching, tactical motif tracking and subscription options.

Free play + $3.99/mo or $39.99 once vs free web tier + Silver/Gold/Diamond plans

Engines, GUIs & PGN databases

Brass Pawn vs HIARCS Chess Explorer

Compare Brass Pawn and HIARCS Chess Explorer Pro on Mac, iPhone and iPad: structured daily tactics and coached play vs multi-million-game PGN databases.

Free play + $3.99/mo or $39.99 once vs separate desktop & iOS paid editions

Engines, GUIs & PGN databases

Brass Pawn vs ChessBase

Compare Brass Pawn and ChessBase: native iPhone, iPad and Mac tactics, endgames and coached Stockfish 18 play vs $200+ Windows tournament databases.

Free play + $3.99/mo or $39.99 once vs $150–$500+ Windows packages & cloud suites

Engines, GUIs & PGN databases

Brass Pawn vs Fritz

Compare Brass Pawn and Fritz across macOS, iPad and iPhone support, Stockfish 18 + Reckless engines, win-probability coaching and pricing.

Free unlimited play + $3.99/mo or $39.99 Pro vs paid Windows versions + web subscriptions

Engines, GUIs & PGN databases

Brass Pawn vs Lucas Chess

Compare Brass Pawn and Lucas Chess: native SwiftUI training on iPhone, iPad and Mac vs open-source Windows/Linux desktop chess utilities.

Free play + $3.99/mo or $39.99 once (AGPLv3 source) vs $0 open-source desktop app

Courses, coaches & AI trainers

Brass Pawn vs CT-ART & Chess King

Compare Brass Pawn against CT-ART 4.0 and Chess King Learn: unified coached play, 14,351 tactics, positional and endgame drills vs separate paid course apps.

Free play + $3.99/mo or $39.99 once vs per-course unlocks or Chess King MAX subscription

Courses, coaches & AI trainers

Brass Pawn vs Duolingo Chess

Compare Brass Pawn and Duolingo Chess: full 8x8 games, Stockfish 18 + Reckless, 14,351 rated tactics and zero ads vs gamified streak micro-lessons.

Free ad-free play + $3.99/mo or $39.99 once vs ad-supported free tier + Super/Max tiers

Engines, GUIs & PGN databases

Brass Pawn vs SmallFish

Compare Brass Pawn and SmallFish on iPhone and iPad: Stockfish 18 + Reckless, win-probability coaching, 14,351 tactics and Mac support vs raw UCI lines.

Free unlimited play + $3.99/mo or $39.99 training unlock vs free open-source iOS app

3D, casual & family chess

Brass Pawn vs Apple Arcade Chess

Compare Brass Pawn with Apple Arcade chess titles: 14,351 tactics, positional drills, Stockfish 18 coaching and permanent ownership vs Arcade rental.

Free forever play or $39.99 permanent unlock vs active Apple Arcade subscription required

3D, casual & family chess

Brass Pawn vs Chess Universe

Compare Brass Pawn and Chess Universe: distraction-free ivory-and-brass boards, zero ads and local Stockfish 18 coaching vs quests, gems and ad timers.

Free ad-free play + $3.99/mo or $39.99 Pro vs ads, gem packs & VIP subscriptions

3D, casual & family chess

Brass Pawn vs Real Chess 3D

Compare Brass Pawn and Real Chess 3D: selectable 2D and 3D brass/bronze sets, Stockfish 18 + Reckless and AGPLv3 ad-free guarantee vs interstitial ad 3D apps.

Free ad-free play forever + optional Pro vs ad-supported free tier + ad-removal IAPs

Courses, coaches & AI trainers

Brass Pawn vs Noctie AI

Compare Brass Pawn and Noctie AI: offline on-device Stockfish 18 and Reckless with $39.99 lifetime option vs cloud-hosted neural bot sparring subscriptions.

Unlimited free engine play + $3.99/mo or $39.99 once vs recurring cloud SaaS tiers

Courses, coaches & AI trainers

Brass Pawn vs DecodeChess

Compare Brass Pawn and DecodeChess: instant offline win-probability move feedback on every game vs cloud-computed XAI game explanations and credit limits.

Free unlimited coached play + $3.99/mo or $39.99 Pro vs metered credits / monthly SaaS

Courses, coaches & AI trainers

Brass Pawn vs Chessvision.ai

Compare Brass Pawn and Chessvision.ai: on-device Apple Vision board photo reading inside an 8-mode chess trainer vs PDF, YouTube and browser diagram scanning.

Free play & board scan + $3.99/mo or $39.99 Pro vs metered scans + annual membership

3D, casual & family chess

Brass Pawn vs ChessKid

Compare Brass Pawn and ChessKid for families: zero accounts, zero text chat, offline Stockfish sparring and Screen Time controls vs school/parent accounts.

Free play + $3.99/mo or $39.99 once vs free basic + Gold annual kid memberships

3D, casual & family chess

Brass Pawn vs SparkChess

Compare Brass Pawn and SparkChess: Stockfish 18 (1400 to full), Reckless 0.10, win-probability coaching and 14,351 tactics vs casual character bots.

Free unlimited engine/online play + $3.99/mo or $39.99 Pro vs limited free bots + paid tiers

Engines, GUIs & PGN databases

Brass Pawn vs En Croissant

Compare Brass Pawn and En Croissant: instant iPhone, iPad and Mac chess training with bundled Stockfish 18 vs desktop PGN repertoire and engine management.

Free play + $3.99/mo or $39.99 Pro (AGPLv3) vs $0 open-source desktop GPLv3 app

Engines, GUIs & PGN databases

Brass Pawn vs Nibbler (Leela GUI)

Compare Brass Pawn and Nibbler: plain-English move coaching, tactics and endgames on iPhone, iPad and Mac vs desktop Lc0 search-tree inspection.

Free play + $3.99/mo or $39.99 Pro vs $0 open-source desktop developer GUI

Training & pricing decisions

Offline Chess App vs Online Servers

What actually works without Wi-Fi? Compare native offline chess training in Brass Pawn with online chess servers across flights, tunnels, battery and focus.

Free offline play + $3.99/mo or $39.99 once vs free/tiered online memberships

Training & pricing decisions

One-Off Chess App vs Annual Subscriptions

Compare 1-year and 3-year chess training costs: Brass Pawn free play, $3.99/month or $39.99 one-off unlock vs recurring premium chess subscriptions and ad tiers.

$0 play / $3.99 mo / $39.99 lifetime vs $80–$170+/year premium recurring tiers

Training & pricing decisions

Private No-Chat Chess App Guide

Why a protocol without text chat beats moderated chat filters: compare Brass Pawn zero-account, zero-ad, Screen Time controllable chess with social chess apps.

Free ad-free play + optional App Store purchase vs ad-supported or per-seat subscriptions

Training & pricing decisions

Native Mac & iPad Chess App vs Browser Tabs

Compare native SwiftUI and compiled ARM64 Stockfish 18 on Mac, iPad and iPhone against WASM browser chess tabs across responsiveness, battery and distractions.

Single Apple Account purchase restores across iPhone, iPad & Mac vs web logins

Training & pricing decisions

Structured Engine Sparring vs Blitz Tilt

Why 20 unreviewed blitz games rarely move your rating: compare coached Stockfish 18 sparring, win-probability grading and spaced repetition against blitz queues.

Unlimited coached engine sparring is $0 free forever in Brass Pawn

Complete 30-comparison matrix

Every comparison page includes three structured specification tables covering engine execution, training datasets, offline availability and multi-year pricing.

Directory of all 30 Brass Pawn side-by-side comparisons and workflow guides
ComparisonCategoryChoose Brass Pawn forChoose the alternative forPricing contrastOffline support
Brass Pawn vs Chess.comOnline servers & analyticsAd-free offline Apple training, coached play & $39.99 one-off optionMassive global matchmaking pools, titled events, clubs & social featuresFree play + 5/day drills; Pro $3.99/mo or $39.99 once vs Gold/Platinum/DiamondFull offline engines & 14,351 puzzles vs online-first platform
Brass Pawn vs LichessOnline servers & analyticsCoached move-by-move engine sparring, 2D/3D Apple UI & positional drills100% free global matchmaking, tournaments, studies & opening explorerFree play + $3.99/mo or $39.99 Pro vs $0 free forever (optional patron)Dual on-device engines & full local library vs server-first with offline bots/puzzles
Brass Pawn vs ChessableCourses, coaches & AI trainersInteractive engine sparring, tactics, positional judgement & live endgame playMemorising structured opening repertoires & grandmaster video/text coursesFree play + $3.99/mo or $39.99 once vs individual course fees + Chessable ProEverything bundled offline on install vs Pro-gated offline course sync
Brass Pawn vs Dr. WolfCourses, coaches & AI trainers760–2800 puzzle ladder, 1400–full Stockfish 18 & $39.99 one-off unlockFirst-week rules learners who want scripted conversational lesson promptsUnlimited free coached play + $3.99/mo or $39.99 once vs recurring subscriptionFull local engines & library without sign-in vs coaching subscription checks
Brass Pawn vs Magnus TrainerCourses, coaches & AI trainersReal 8x8 chess calculation, spaced-repetition motifs & master game takeoverGamified arcade mini-games & themed casual drillsFree play + $3.99/mo or $39.99 once vs subscription membershipComplete offline suite bundled at install vs partial lesson caching
Brass Pawn vs Shredder ChessEngines, GUIs & PGN databasesModern SwiftUI interface, 14,351 puzzles, positional judgement & free engine playLong-time fans of Stefan Meyer-Kahlen’s adaptive Shredder engine & tablebasesFree download & unlimited play (Pro $3.99/mo or $39.99) vs paid upfront app + desktop licensesBoth run offline on device; Brass Pawn adds Game Center & 900 Watch games
Brass Pawn vs AimchessOnline servers & analyticsNo-account offline Apple practice, live coached games & one-off Pro unlockImporting hundreds of Chess.com/Lichess games for automated opening & time statsFree play + $3.99/mo or $39.99 once vs recurring cloud analytics subscription100% offline training & engines vs cloud-dependent account syncing
Brass Pawn vs Chess TempoOnline servers & analyticsClean native iOS/iPadOS/macOS offline training, coached play & 2D/3D boardsCustom browser puzzle filters, community problem comments & opening treesFree play + $3.99/mo or $39.99 once vs free web tier + Silver/Gold/Diamond plansFull native offline app vs online web database
Brass Pawn vs HIARCS Chess ExplorerEngines, GUIs & PGN databasesUnified iPhone, iPad & Mac daily tactics, positional judgement & instant coached playHeavy macOS/Windows PGN database management, opening books & tournament prepFree play + $3.99/mo or $39.99 once vs separate desktop & iOS paid editionsBoth run offline; Brass Pawn requires zero database or UCI configuration
Brass Pawn vs ChessBaseEngines, GUIs & PGN databasesNative Apple daily improvement, offline Stockfish 18 sparring & low one-off costTitled/FIDE tournament dossier prep, Mega Database & reference noveltiesFree play + $3.99/mo or $39.99 once vs $150–$500+ Windows packages & cloud suitesNative offline iOS, iPadOS & macOS vs Windows desktop + web companion apps
Brass Pawn vs FritzEngines, GUIs & PGN databasesNative iPhone, iPad & Apple Silicon Mac play with Stockfish 18 & RecklessWindows desktop players invested in ChessBase accounts & Fritz personalitiesFree unlimited play + $3.99/mo or $39.99 Pro vs paid Windows versions + web subscriptionsCompiled native offline Apple app vs Windows local install / browser cloud app
Brass Pawn vs Lucas ChessEngines, GUIs & PGN databasesPolished native iPhone, iPad & Mac experience with zero setup & Game CenterFree Windows/Linux desktop tinkering with dozens of bundled UCI enginesFree play + $3.99/mo or $39.99 once (AGPLv3 source) vs $0 open-source desktop appBoth run 100% offline; Brass Pawn brings it to iPhone, iPad & native macOS
Brass Pawn vs CT-ART & Chess KingCourses, coaches & AI trainersAll 8 modes, coached play, 900 games & 14,351 tactics inside one clean Apple appClassic Blokh/Convekta hand-composed computational puzzle workbooksFree play + $3.99/mo or $39.99 once vs per-course unlocks or Chess King MAX subscriptionFull offline play & puzzles in one bundle vs per-course downloads across apps
Brass Pawn vs Duolingo ChessCourses, coaches & AI trainersSerious calculation, full coached games, endgame conversion & zero ads/streaksAbsolute beginners already inside Duolingo who want casual daily streak promptsFree ad-free play + $3.99/mo or $39.99 once vs ad-supported free tier + Super/Max tiersFull local Stockfish 18 & 14,351 puzzles offline vs online-first streak app
Brass Pawn vs SmallFishEngines, GUIs & PGN databasesGuided tactics, positional & endgame modes, plain-English coach & Mac supportQuick free raw Stockfish line inspection & PGN browsing on iOSFree unlimited play + $3.99/mo or $39.99 training unlock vs free open-source iOS appBoth run Stockfish locally offline; Brass Pawn adds Reckless 0.10 & 8 training modes
Brass Pawn vs Apple Arcade Chess3D, casual & family chessPermanent free/one-off access, deep tactics, endgame verification & move coachingCasual 3D environments when you already pay monthly for Apple One / ArcadeFree forever play or $39.99 permanent unlock vs active Apple Arcade subscription requiredOffline forever without subscription checks vs requires active Arcade entitlement
Brass Pawn vs Chess Universe3D, casual & family chessCalm, distraction-free study with zero ads, zero gems & real Stockfish coachingCartoon avatars, cosmetic unlock quests & cross-platform casual matchmakingFree ad-free play + $3.99/mo or $39.99 Pro vs ads, gem packs & VIP subscriptionsFull offline training & dual engines vs online quest & currency economy
Brass Pawn vs Real Chess 3D3D, casual & family chessAd-free 2D & 3D carved/bronze sets, Stockfish 18 coaching & 14,351 puzzlesCasual Android/iOS 3D camera-spin matches without structured trainingFree ad-free play forever + optional Pro vs ad-supported free tier + ad-removal IAPsOffline without cached ad SDKs or trackers vs ad-SDK bundled mobile game
Brass Pawn vs Noctie AICourses, coaches & AI trainersOffline iPhone/iPad/Mac play, zero cloud latency, free sparring & $39.99 one-off ProBrowser-based neural human-like sparring & custom opening flashcard generationUnlimited free engine play + $3.99/mo or $39.99 once vs recurring cloud SaaS tiers100% offline local engine execution vs requires live internet connection to cloud GPUs
Brass Pawn vs DecodeChessCourses, coaches & AI trainersUnlimited free move-by-move coaching offline on iPhone, iPad & MacMulti-paragraph deep cloud threat breakdowns of imported PGN games in a browserFree unlimited coached play + $3.99/mo or $39.99 Pro vs metered credits / monthly SaaSInstant local evaluation with zero network wait vs cloud server queue & internet required
Brass Pawn vs Chessvision.aiCourses, coaches & AI trainersScanning a real board offline via Apple Vision, then playing & training in one appBrowser extension scanning of YouTube videos, eBooks & multi-page chess PDFsFree play & board scan + $3.99/mo or $39.99 Pro vs metered scans + annual membership100% on-device Apple Vision + local Stockfish 18 vs cloud recognition API
Brass Pawn vs ChessKid3D, casual & family chessZero-account offline training, zero-chat protocol & one-off family device useClassroom coach dashboards, animated kid lessons & supervised kid clubsFree play + $3.99/mo or $39.99 once vs free basic + Gold annual kid membershipsFull offline play & puzzles with zero login vs cloud-managed parent/kid accounts
Brass Pawn vs SparkChess3D, casual & family chessStructured 760–2800 tactics, positional judgement, endgame verification & free playLight cross-platform games against named low-rating cartoon botsFree unlimited engine/online play + $3.99/mo or $39.99 Pro vs limited free bots + paid tiersFull library & both top engines offline free vs full bot roster gated behind paid editions
Brass Pawn vs En CroissantEngines, GUIs & PGN databasesiPhone, iPad & Mac zero-setup training, coached play, Rush & Game CenterDesktop-only PGN repertoire building, multi-million-game reference DBs & UCI tinkeringFree play + $3.99/mo or $39.99 Pro (AGPLv3) vs $0 open-source desktop GPLv3 appPre-bundled offline on iOS, iPadOS & macOS vs desktop-only after downloading engines/DBs
Brass Pawn vs Nibbler (Leela GUI)Engines, GUIs & PGN databasesEveryday chess players wanting coached games, puzzles & iPhone/iPad/Mac polishEngine researchers inspecting Leela Chess Zero WDL nodes & search graphs on desktopFree play + $3.99/mo or $39.99 Pro vs $0 open-source desktop developer GUIReady out of the box on iPhone, iPad & Mac vs requires manual desktop Lc0 + weights setup
Offline Chess App vs Online ServersTraining & pricing decisionsFlights, subway commutes, zero-disconnect sparring & quiet deliberate practiceLive global human rating pools, titled broadcasts & community tournamentsFree offline play + $3.99/mo or $39.99 once vs free/tiered online memberships100% local engines, 14,351 tactics & 900 games vs network-dependent lobbies & cloud review
One-Off Chess App vs Annual SubscriptionsTraining & pricing decisionsPredictable $0 free play or $39.99 permanent ownership with zero ads everPlayers who actively consume daily video courses, streamer events & cloud coaching$0 play / $3.99 mo / $39.99 lifetime vs $80–$170+/year premium recurring tiersLocal compute costs $0 per game to run, enabling a sustainable one-off unlock
Private No-Chat Chess App GuideTraining & pricing decisionsZero stranger DMs, zero ad SDKs, no account sign-up & Screen Time Game Center lockSocial clubs, team forums & coach-managed school messagingFree ad-free play + optional App Store purchase vs ad-supported or per-seat subscriptionsAll offline progress stays inside the device container with zero telemetry
Native Mac & iPad Chess App vs Browser TabsTraining & pricing decisionsCompiled native Stockfish 18, zero tab clutter, touch/pointer polish & offline playZero-install shared computers, Chromebooks, Windows/Linux & URL link sharingSingle Apple Account purchase restores across iPhone, iPad & Mac vs web loginsAlways available from Dock or Home Screen offline vs tab reloads & WASM re-fetches
Structured Engine Sparring vs Blitz TiltTraining & pricing decisionsImmediate win-probability move feedback, spaced-repetition motifs & zero tiltTesting practical clock nerves & psychological resilience against unpredictable humansUnlimited coached engine sparring is $0 free forever in Brass PawnPractise anywhere offline without risking an online rating during a tired commute

Frequently asked questions

Does Brass Pawn replace an online chess server like Lichess or Chess.com?
It replaces the daily training half rather than large-pool tournament play. Brass Pawn gives you offline Stockfish 18 and Reckless 0.10 sparring, win-probability move coaching, 14,351 tactics puzzles, 116 positional exercises, 15 endgame drills, 900 decisive master games and zero-chat Game Center matches on 3, 5, 10, 15 or 30-minute clocks. If you want thousand-player Swiss arenas, clubs or correspondence leagues, pair Brass Pawn with an online server.
Why does Brass Pawn not include an opening repertoire trainer?
Opening preparation is memorisation against a specific repertoire tree you choose and maintain, which belongs in a dedicated course or PGN database tool. Brass Pawn focuses on skills that transfer across every opening: tactical motif recognition, quiet positional judgement out of the opening, and converting or holding canonical endgames against Stockfish.
What is free in Brass Pawn compared with subscription chess apps?
Playing chess is free and unlimited forever: coached games against Stockfish 18 (1400 to full strength) or Reckless 0.10, real-time human matches over Game Center, Today stories, and all 900 decisive master games in Watch. Metered training modes — Tactics, Rush, Positional judgement, Endgames and Guess the Elo — include 5 free attempts each per day (resetting at 9:00 AM local time). Brass Pawn Pro removes those daily counters for $3.99/month or a $39.99 one-off unlock, with zero ads in either tier.
How are Brass Pawn claims verified in these comparisons?
Every Brass Pawn specification on this page comes directly from the public AGPLv3 repository: puzzle and game counts from bundled data files, engine versions from compiled Stockfish 18 and Reckless 0.10 sources, and privacy claims from the shipped iOS/iPadOS/macOS codebase.

Brass Pawn

Tactics, positional judgement, endgame technique and coached play, with the engine running on the device itself. No account, and nothing collected — apart from what online play needs: that you are online, and the friends you make.

Chess practice: offline analysis, puzzles and friends

Free software under the GNU Affero General Public License v3. Read the source.

© 2026 Mincho Milev. Brass Pawn is free software.

Stockfish © the Stockfish developers, GPLv3. Puzzles and games from the Lichess database, CC0. Not affiliated with Apple, Lichess, the Stockfish project or the Reckless project.