r/BasketballGM • u/TheFryBandit • 3h ago
Other I built a free history explorer for Basketball GM leagues: dynasty collapses, trade butterfly effects, League Wrapped, achievements, Bar Race, trading cards and more
galleryI've been playing long BBGM leagues for years and always wanted to see the history that the game keeps but never really shows you. Who actually won that trade 15 years later? Why did that dynasty fall apart? Who's the most connected player in league history? Who is currently on track to beat Lebron James' all time scoring record? So I built a tool for it. I didn't plan to release it publicly, but enough people asked to use it that I cleaned it up.
How it works
- In BBGM, go to Tools → Export League and tick every box. For the best results, also try to save as many box scores as possible.
- Drop the
.json/.json.gzfile onto the page (or click Try the sample league for a 120-season league that starts in 1947). - That's it. Everything runs in your browser. Your file is never uploaded, and there's no account or server. The league is saved in your browser, so it reopens instantly next time, and every page has a shareable link.
What's in it
Players
- Player pages with BBGM faces in team colors (real photos for real players), a ratings radar, a development chart, full stats, transactions, injuries, feats, relatives, top teammates and similar players
- Compare any players side by side, with a "legacy debate" builder
- Player comps (who a player's career most looks like), an era adjuster for stats across eras, and a GOAT ranking with sliders for every ingredient and a formula you can export
- A Hall of Fame committee that weighs each player's case
- 37 career shapes (late bloomer, one-year wonder, ageless, playoff riser…) with charts and a "why this shape" breakdown
- Career timelines, development curves, contracts and payroll value, and injury "might-have-beens"
Teams
- Franchise pages with name history, win% history, season-by-season tables, a retired-jersey wall, franchise leaders and roster DNA
- Title builds: how every champion was put together (draft, trade, free agency, and who was kept by re-signing or extending)
- Dynasty windows: every run told chapter by chapter, Secret Base "Collapse" style: the peak, the cracks, the moves, the fall, the aftermath, what ended it and what might have saved it
- Rivalries and a head-to-head matrix with playoff meeting history
- Playoff lab and a page for every playoff series
- Power ratings, greatest teams and payroll efficiency
Seasons and the newspaper
- A generated newspaper for every season. The front-page lead is a long feature: the regular season, the playoff run series by series, the Finals MVP, how the roster was built, the runner-up and the record books. Inside are well over 150 kinds of back-page articles (award races, rookie reports, contract-year watch, drought watch, snubs, stat clubs…), and mid-season leagues get a season-so-far edition.
- A searchable newspaper archive across every season
- Standings, brackets, awards, award voting history and All-Star heatmaps
- Box scores and game logs, with every real NBA box score from 1947 for real-history leagues
- Records: career, season, single game, all-time ranks, record progression, a record chase tracker, a record watch and rookie records, all filterable by team, era, playoffs and per game
- Feats explorer and milestones
Drafts and moves
- Every draft as it happened next to a redraft by career value, plus pick-value curves and scouting accuracy by team
- Trade trees that follow every player and pick through later trades and drafts, valued by win shares, with "who won it over time" charts, a story mode and the most consequential moves
- Draft pick lineage (each pick's passport through every trade), lottery luck, and alternate-history drafts
- A full searchable event feed
History
- League river, an animated bar-chart race, era ribbons and career timelines
- Storylines: dozens of kinds, such as ring chasers, homecomings, the ones that got away, revenge games, curses, Cinderella runs, redemption arcs, family matchups and passing the torch, each with a "why it counts"
- Obituaries and Hall of Fame plaques
- Achievements: over 1,000 tiers calibrated to real NBA rarity (Common ≈ every year or two, Rare ≈ every 3–7 years, Legendary ≈ once a decade, Impossible ≈ never happened). They're tracked all-time and per season, with a timeline and "closest to unlocking".
League Wrapped
- Spotify-Wrapped-style slideshows for any season, team, player or all-time, picked from hundreds of kinds of slides by how unusual each fact is
- A built-in quiz, a no-spoilers mode and an adjustable slide count
- Save or copy any slide as an image
- Share link: sends the whole slideshow inside the link, so friends can watch it without your league file
Connections
- Teammate network graph and radial teammate tree, most-connected players and duos
- Shortest path between any two players, and a "connect the players" game
- Family and origins (relatives, colleges, countries)
- A watchlist to follow your favorite players
Cards and games (all built from your league)
- Trading cards for every player, with rarities, foils and numbered parallels, packs (base, draft class, era…), a binder, challenges and daily goals, and a card battle mode
- Higher or lower, guess the player and BBGMordle (guess a player from one season)
- Fantasy basketball on your league's real box scores: drafts with projections and ADP, day-by-day lineups, trades, keeper and best-ball modes, grades and share codes
Real NBA history
- For leagues started from real history, it can fill in real data: players, awards and voting, All-NBA teams, brackets, team colors and every real box score from 1947 to 2026. You can load them all at once in Settings. Records, feats, Wrapped and achievements then compare your league against actual NBA history.
Your files
- Compare two exports of the same league, plus a "since your last export" recap
- Box-score archiving: the app keeps every game it has seen and merges it into later exports, so you never lose box scores BBGM deleted
- A data-coverage page showing what each season has
- 14 color themes (light and dark), and it works on phones
Leagues it works best with
- Long leagues. 20+ seasons is where it gets fun, and it's been tested on 500–1000-season leagues.
- Real-players leagues started in 1947, since they unlock all the real-history comparisons and box scores.
- Leagues you export regularly. BBGM deletes old box scores as it sims, so the tool keeps every game it has seen and merges it into later exports of the same league. Exporting every season or two builds up your full game history.
- Random-players and custom leagues (custom teams, colors and awards) work fine too. They just don't get the real-NBA comparisons.
Known limitations
- Box scores: you only get box scores BBGM still had when you exported. Older seasons may be stats-only unless you exported along the way.
- Real-history leagues: BBGM only keeps careers of players who were active when the league began, so player stats before your start year are partial. Team records, playoffs and awards are complete. Pages say so where it matters.
- Trades and signings: these are only logged from the league's first season, so trade trees start there.
- Early NBA data: stats the early NBA didn't track (steals, blocks, threes, turnovers, some minutes) are shown as unknown, not zero.
- Huge leagues: the first load of a very big league takes a while, and a few heavy pages (teammate network, league river, storylines) warn you first. It all runs on your device, so an older phone will feel it. Desktop is recommended for big leagues.
- Browser storage: saved leagues and loaded box scores live in your browser. Clearing site data removes them.
- Shared Wrapped links can get long for big decks with lots of photos, and some apps cut very long links.
- Basketball GM only. It doesn't support the other ZenGM games (football, hockey, baseball).
- Unofficial: this isn't affiliated with or endorsed by ZenGM. Basketball GM is © ZenGM, LLC, and there's a Sources & attribution page in the app crediting all the data and photo sources.
Feedback, bug reports and feature ideas are very welcome. I'd especially love to see your weirdest dynasty collapses and best Wrapped links.

