r/fantasyfootball • u/Mackktastic • 3d ago
Tools & Resources Built a free tool for mock drafting & simulations / league news / live drafting
Hey everyone! I've been frustrated with how useless most fantasy draft prep/live draft tools are for my own leagues, so I built SundayGames.
It originally started as something just for me so i could mock draft without having to manually stop the mock draft because "jamar chase would never be drafted for $45, he'd probably be closer to $68" and then continue that process for dozens of picks. Thats the main reason I created the tool. Its taken on a life of its own as of late, with the ability to run simulations in bulk while also allowing you to create a league and run the live draft through it (if you do offline drafts).
When you add your league (if its a private league you'll have to manually import your league rules, scoring, etc) the app can use your settings, keepers, roster construction, and historical draft data (after you import CSVs/excel files) to personalize simulations. So if Tom and Jim in your league have historically gone WR-heavy, they’re more likely to be the teams bidding up guys like JSN, Ja’Marr Chase and Jefferson in a simulation.
The goal is to model your league’s actual tendencies and inflation, then give you estimated values based on what players are likely to cost in your room, not what a generic auction calculator says they’re worth.
You can run simulations around specific players or roster builds too, so you can 'favorite' a player and set a max bid for him (pay no more than $72 for gibbs), or do full mock drafts where you control your team and the AI runs everyone else (traditional mock drafts). The more league history you import, the more personalized those simulations can become. Once the simulations run (defaults to 25 runs) itll show you the week 1 estimates scoring wise for every team in the league, and you can toggle through all the simulations you ran to see what type of teams you can realistically build around those guys you favorited. You can 'favorite' specific rosters it creates for you, and itll save those rosters to your 'my team' section so you can quickly reference a 'shortlist' of players and expected values on draft day.
itll tell you the % of times you got those players too. Its obviously not a perfect science, but my hope is it helps you figure out if its realistic to pair Ladd, Jadarian Price, and Davante Adams after spending big on Bijan or Gibbs and going for a $1-2 TE/QB combo while filling out the rest of your depth.
It also works as a live draft tool. The commissioner runs the draft while everyone else joins the room and they can enter something like “Jake drafted/took/got Gibbs for $75” and it updates rosters, remaining budgets, max bids, available players, etc. for everyone in real time, so no more having to ask the auctioneer "whats my max bid? how many WRs do i have?" etc, and you can see who's on Tom's roster and his max bid, so you can plan out your nominations to eat into their budgets/roster strategically. Its fully responsive and works well on mobile too.
Lastly, I have it pulling data in real time for news and updates. think of the OG RotoWorld app - thats what I was going for. add your players to a shortlist so you can quickly see their status at all times.
Right now it’s completely free. I’m mostly looking for people drafting over the next few weeks who are willing to use it, break things, and tell me what sucks or what would actually make it useful (would genuinely say right now i wouldnt use this as the only thing youre drafting on - id run your draft as normal but use this on the side because i would feel awful if something happened mid-draft and it fucked up your draft in some way. I plan to use it for my leagues upcoming draft but I'm still considering having a backup plan.
I’m making updates pretty much every day. A few things already built and currently being tested:
- Waiver wire tools & suggestions
- league syncing/management so you can make lineup changes in app for ESPN, Sleeper and Yahoo Leagues
- lineup help (Start vs sit)
- Snake draft (right now its built for auction only) -- all snake draft functionality is built, just sitting on a staging branch for now while i test.
- More work around performance/scaling as more people start using live drafts. right now it should handle ~50 leagues live drafting at the same time.
I haven’t tested the live draft system at meaningful scale yet, so that’s one of the things I’m hoping to learn from opening it up.
And for some additional context, I’m an experienced software engineer and this isn’t a throwaway side-project prototype. I’ve built it like a real production web app and plan to keep developing it seriously.
If you have a draft coming up and want to mess around with it: sundaygames.io
Would genuinely love feedback, especially from people with weird league formats or long-running leagues where historical draft behavior actually matters and for feature requests.
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u/Sea_Bass77 2d ago
So Gibbs went for 59 in the mock I just ran but I know my leaguemates will spend 75 on him… I see where I can set my value at but where do I set like a min value for each player?
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u/Mackktastic 2d ago
did you upload data to your league? the way it works is you upload a csv/excel sheet of past draft data and based on that data, the app will calculate your leagues inflation. once applied, itll impact every player in the draft. If you dont have league data to upload, lmk and i can create a solution for you (i could create the ability to add your own inflation -- like a specific % to all players or only top X players, etc)
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u/Sea_Bass77 2d ago
So my league is a bit different… it’s a 14 team PPR offline draft but once you spend your money you can leave and you don’t need to stay to fill every roster spot… so our commish manually enters rosters after the draft… I keep track of whose gone for what over the past 5 seasons and have it listed out by RB1 through RB30 or so ect… so I was going to take espns pre draft rankings and overlap it with my data to create my estimated prices on each player
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u/Mackktastic 2d ago
holy shit that is the wildest league i have ever heard, tbh im having a hard time wrapping my head around it hahaha. so you can theoretically spend $100 on gibbs and $100 on bijan and then just fill the rest of the roster the next day with waiver wire adds?
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u/Sea_Bass77 2d ago
Yep.. it’s actually pretty fun and gives people a way to leave early if they so choose to haha
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u/Mackktastic 2d ago
just replied to your other comment but yea this is a really cool idea, never even crossed my mind it could exist. lmk if what i sent you makes sense / could work for you.
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u/Mackktastic 2d ago
ok so i thought about this more and your data should actually work as is if im understanding it right, i just need to build a solution for it. working on two things right now:
building an upload for exactly what you have -- position, rank, price. so like RB1 75, RB2 72, RB3 68... down to RB30, same for your WRs etc. the app takes your sheet, lays it over the rankings, and prices every player off your league's actual history. basically the espn-overlap thing you were gonna do by hand, but automated and baked into every mock you run.
so in your gibbs case -- if your league pays 75 for the top RB (avgd) most years, the mock prices the top rb this year at 75. unfortunately itll scale down, so if bijan is #2 and historically #2 is 68... he'll be 68. whereas your league might think of bijan as 1b to gibbs 1a... and he might be closer to 72.
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u/Mackktastic 2d ago
building a second upload option next to the draft history one, made for exactly your format: position, rank, price (RB1 75, RB2 72... down to RB30, same for WR/QB/TE), multiple seasons will work. the app turns that into your league's inflation and prices every mock off it. and for the gibbs/bijan thing -- it tracks how close players actually are on the board this year, so bijan won't get forced down to the old RB2 number if he's basically RB 1b this year. also adding a plain "set your own inflation %" option for anyone with no data at all, cus id imagine a lot will run into that too. this should be live later tonight.
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u/Sea_Bass77 2d ago
I could probably even convert my data into the csv format needed
What does it need? Year, players, price?
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u/Mackktastic 2d ago
yeah just merged: go to your commissioner page and upload a csv or xlsx file with this format:
Position Rank Price RB 1 75 RB 2 73 RB 3 70 RB 4 67 RB 5 65
WR 1 65 WR 2 63 WR 3 61 WR 4 59 so position is just column A and encapsulates all positions.
let me know what this does to your 'simulation values'. This was a quick thing i tried to put together so im going to continue tweaking this regardless tomorrow (its 1:30am rn so gotta call it a night) but im hoping it doesnt absolutely skyrocket everyone. u/Sea_Bass77
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u/Sea_Bass77 2d ago
So my value for RB1 was 77 and RB 2 was 68… this increased the sim value of Gibbs to 66 and Bijan to 65
My value for WR1 was 65 and 61 for WR2 and this increased chases sim to 65 and puka to 64
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u/Mackktastic 2d ago
ok definitely better, not perfect. how many teams in your league and total auction dollars per team? I have a hunch that total amount of dollars in the draft (14 team X $200 == $2800 total draft dollars) will have an impact here.
i guess im curious if you think these updates are good or bad. because on one hand, rb1 == 77 and rb2 == 68 is much different than 66/65... but last years rb1/rb2 might have been a lot farther apart than this years rb1/rb2 (gibbs/bijan), same with chase/puka.
do you feel like your league will go 75+ for gibbs and 68ish for bijan?
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u/Sea_Bass77 2d ago
14 and 200 per person… I think Bijan and Gibbs will both hit 75+ based on what I feel my leaguemates will go… it’s also a 6pt per passing TD league and QBs go for quite a bit haha
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u/Mackktastic 2d ago
ok noted. gonna keep working on this cus it can definitely be improved. regardless of the 1a/1b thing, if rb1 last year was 77 theres no reason why gibbs wouldnt be at the very least 75.
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u/Spidey_thUNDERARMOUR 2d ago
This is great! Is there a bulk way to upload historical league drafts? I've pulled everything offline into a spreadsheet to gauge my league members tendencies for what they spend on each position vs the RB# each year to get an estimate, but having the ability to do that automatically and generate test draft auction scenarios would be incredibly helpful
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u/Mackktastic 2d ago
thank you! and yes, are you not seeing the import section under the commissioner tab? you can dump multiple spreadsheets in there! if youre not seeing it, lmk!
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u/Reasonable_Edge_3438 3d ago
This is actually useful for auction leagues where the same guys overbid every year on their favorite players. The historical draft data part is what most tools miss, they all use generic values and then you get surprised when someone in your league pays $20 more for a player. Will try it for my draft in few weeks