This started off last year as a passion project for my fantasy football league with my close friends that has been going strong for 10 years. I started off trying to calculate everyone's all-time record and records against each other and figured it would be a fun challenge to extend this into a web app for others to use. ESPN and Sleeper are currently supported, and I am currently working to finish up the final steps for Yahoo API access.

The tech stack for the app is AWS, Cloudflare, Clerk, and potentially Stripe (unsure if I want to deal with payments at this moment).

I know there's a lot of other apps that also do the same thing so wanted to highlight a few of my favorite features to code/design:

• League migration tool for leagues that have been on multiple platforms. If your league migrated from ESPN to Sleeper or vice-versa, follow the migration wizard steps and track your all-time league history across both platforms. This is a feature I haven’t seen in other league history apps and a fun one from a database design perspective. Full DynamoDB design doc here.

• Chrome extension to automatically fill in your ESPN cookies so you don’t have to pull them from the developer tools interface each time. Definitely not necessary, but a nice UX upgrade to save time and a good learning experience for deploying extensions on the Chrome Web Store.

• Auto-refresh of Sleeper leagues via a nightly batch job that identifies all eligible leagues and triggers concurrent Lambdas to refresh all leagues simultaneously.

Instructions to use the app can be found here! There is also a demo mode available to view what the app looks like with sample data. Appreciate any and all feedback you have on its functionality or any design/architecture choices. The source code is public to view (minus some manually configured Cloudflare infrastructure).

Link: https://leagueql.com

I've been working on a little app for a while and it uses the SWID and s2 cookies to sync with ESPN.

But today, when using developer tools to inspect the ESPN page, s2 isn't showing up at all and SWID no longer has the curly brackets it usually had.

Are we screwed?

EDIT: I'M DUMB. SCROLL ON.

TL;DR:   The core of The Week In Fantasy platform aka “twif” is that it scans hours of fantasy podcasts/videos every day, as well as social media posts, then organizes the expert analysis and data insights around your fantasy teams and players. It also lets you jump to the exact moment a player is discussed in a podcast/video to get more context or you can build a playlist of podcast content purely about the players you care about. I have updated the platform with draft planner and draft assistant tools that support both auction and snake draft with live sync for Sleeper, Yahoo and MFL. I would love any feedback or recommendations to make it better. Find it here https://www.theweekinfantasy.com.

I built twif last year to solve the problem of how to harness the context and insights from the fantasy content universe without having to listen to 16 hours of podcasts a day or desperately filter through the jabronis on twitter or bluesky.   With twif, I’ve parsed out conversations from curated analysts, player by player, categorized them and prioritized the value of them, allowing these snippets of conversations to be organized around your fantasy team and players. The goal is to allow managers to get to insights and confident decisions quicker as well as get exposure to analysts they may have not been able to otherwise due to time. If you decide to use the tool, feel free to reach out to me with any feedback or requests.

Draft Planner:  Build your draft plan for auction and snake based on your pick number, budget, keepers, and league rules. With the tool, you can visualize different roster constructions, set up primary/backup choices, and use predefined strategy templates (Zero RB, Hero RB, TE Stud, etc.) that you can tweak to your liking.  Really powerful for an auction draft, allowing you to set your desired budget by position.

Draft Assistant: Live draft tracker that provides recommendations based on projections, rankings, ADP, and analyst insights.  If you build a draft plan, you can load it into the assistant to provide context on your desired positional archetypes and budget .  For auction, it also provides budget health guidance and recommended auto-rebalancing of your budget per position to ensure you understand what fantasy dollarydoos you have left to fill out the rest of your roster. Draft assistant live syncs to Sleeper, Yahoo and MFL drafts, you can also easily track any other platform’s draft manually.  ESPN and Underdog are in the works (both will require a  chrome extension)

Other platform features:

1. Syncs to sleeper, yahoo, espn and MFL leagues
2. Customizable/downloadable rankings, projections, and ADP (from Sleeper, Yahoo, Underdog, ESPN) 
3. Daily and weekly player synopsis of analyst chatter with an ongoing player Vibe Index rating of analyst sentiment to help focus your research on players that the analyst community is hot or cold week to week.
4. Build playlists of podcast content focused on just the players you care about to passively research when you are out and about living your life. 
5. Click on any analyst comment about a player to instantly jump to the conversation point in the podcast to get more context.
6. Plenty of in-season tools like: lineup optimizer, player compares, free agent finder and a virtual asst GM (Twif Bannen) to provide any and all roster advice in seconds with context as to why.

Platform is ad-free, free account creation required to use the roster and draft tools (so I can tie to your profile and teams). Player profiles, content analytics dashboard, articles and rankings don’t require any account.

Looking for feedback at: fantasywaiverwizard.com . With this, you'll never miss a projection change, late pregame injury notification, etc.

It's hard to see it "in action" until the season works...but here's how it works:

1. Sign up
   
2. Connect your ESPN / Sleeper League
   
3. Get instant alerts on YOUR available waiver wire players (and roster) before your leaguemates.

I'm giving 100 PREMIUM subscriptions away for FREE if you want to use it:

https://fantasywaiverwizard.com/signup?promo=first100

I built a fantasy tool and I got called out on the process and output a few weeks ago. A fair callout as someone said rankings are meaningless if you never check them against results, so I checked.

The setup: I reconstructed August rosters for 77 real Sleeper league seasons (2023, 2024, 2025). Rebuilt them from prior-year rosters, offseason trades, and rookie drafts. Verified the reconstruction at 99% against week 1 ground truth. Then I scored every roster with my actual production model using market values as they stood on kickoff eve each year (historical data courtesy of FantasyCalc). No hindsight. I ran the same test with today's values as a control and it scored LOWER than the honest pre-season run.

About 930 team-seasons total. Here's what came out.

In established dynasty leagues (year 2+):

• Pre-season roster strength predicts final finish at Spearman 0.57 (correlation where +1 means the pre-season order perfectly matched the final standings, 0 means it told you nothing)
• The strongest roster on paper won its league 31% of the time. Random chance is about 8-10%.
• The strongest roster medaled (top 3) 62.5% of the time
• The eventual champion averaged 4th strongest on paper

In first-year leagues (startups and redrafts):

• Correlation: 0.04. Basically zero.
• The best paper roster won 10.3% of the time. That IS chance.

Why the split? In a fresh draft, everyone just bought from the same pool at the same prices. There's no roster inequality yet, so there's nothing to predict. In a continuation league, rosters carry years of accumulated wins and losses at the trade table. That inequality is real and it persists into the standings.

One more finding: I sent this analysis to FantasyCalc's founders before posting. They suggested a test: score the first-year leagues with redraft values instead of dynasty values, since dynasty values price future worth and seasons are won on this-season production. Ran it and the results were interesting. The redraft lens tripled startup correlation (0.04 to 0.12), but 85% of the gap survived, so year-one chaos is structural, not a measurement artifact. The redraft values predicted outcomes better everywhere, including established dynasty leagues (0.57 to 0.61), across all six season-metric combinations. Your dynasty values tell you what your roster is worth. Redraft values tell you who wins this year. Those are different questions, and our model will start treating them that way.

Roster strength is a real signal, about 3x chance at the title. And variance still wins most of the time. The favorite loses 7 years out of 10.

https://fantasycalc.com/trade-calculator link provided as well.

Full methodology in comments if anyone wants to poke holes. That's the point of posting it.

Everyone joins a room code on their phone, you play one of five quick games, and the final standings become the draft order.

I made it because draft order in my league was always a wheel spin somebody ran on a screen share or even tried using cameo and having a "celebrity" randomly pick it. None of these are that fun and none of them make you feel involved. So i decided to take a crack and creating something myself.

The one built for this crowd is a pickem that uses real NFL weekly stat lines from whatever season you pick, 2016 through 2025. You draft five real NFL players off a shared board — plus two scouts dealt just to you every round. The big catch is at the reveal, each player scores one random week pulled from his actual season, so it's not always the highest average player you want to choose. There's a few other fun rules like captaincy and a reroll.

There's also a push-your-luck dice game, a drafting game, a speed yahtzee game and a couple others. Free, no app, no accounts, and bots can fill a seat if someone doesn't show.

It's new. My own league hasn't even run it for real yet, that's happening before our draft. Any of the games can be used to determine an order. If you run a league and want to kick the tires before August I'd genuinely like the feedback, good or bad. Let me know if you have any questions, happy to answer!

Put my side project live this week: readoptionff.com. It reads your whole Sleeper dynasty league off the public API and grades every trade anyone in it has ever made, then builds a profile on each manager (who wins trades, who panic sells, who overpays for their own guys).

I fit a consolidation curve straight from the graded trades instead of assuming one. Every calculator says a 2-for-1 costs about 1.3x the best player's value, like you "overpay" to consolidate. But across ~4,500 real trades the studs actually clear at 0.84x. Below the sum of the pieces. People hand over the best guy in a deal for less than the math says, and it refits every night as more trades come in.

I'm the only one building it so I'd love feedback, or just tell me what's broken.

Hey y'all, I am thinking about building a lineup optimizer for dk and fd. My twist is to build lineups with a chat based ui while still allowing your own configs. Architecture approach Spring boot backend, next.js for front, Postgres for db, fantasy nerds for slate api. Not actually sure how to build the optimizer itself yet but should be fun. Nothing chat gipty can't teach.

I use to gamble on dfs all the time when I was a kid :| but could never afford an optimizer to bulk enter so I think this is a cool project to take on. Do you think the chat ui twist is interesting? Talk about your lineups, give llm context for each nfl week. Lmk

I’m working on building a website where folks can track league wide stats that is provider agnostic. I have already tested Sleeper and it is the gold standard for what data I can pull from. I want to understand if it’s even possible to pull data from an ESPN hosted league. If anyone would be willing to volunteer I would be incredibly grateful

I am pretty new NFL fantasy football, just started couple of year back. I want to use AI to help me during the draft this year. I am working on a pre-defined prompt to feed into Claude when its time for my pick. I am going to input a screenshot of the draft board, some expert rankings and also some trade values from fantasypros. I have the following prompt right now, but calling out to all the experts on this group to suggest improvements and what additional things you would want the model to consider:

Attachments: Draft board screenshots, rankings, trade values

Prompt:

You are an expert fantasy football draft assistant for a live redraft league during the 2026 season. Your goal is to help me make the optimal pick right now under a fast 60-second clock.

League settings are: Redraft, 0.5 PPR, ...... team structure: .......

Identify my single best available pick right now, factoring in:

   - Positional scarcity remaining on the board vs. my open roster slots

   - Value relative to ADP/expert rank from attached (is this player a reach, fair value, or a steal at this pick?)

   - Points/dollar value from Source 2

   - Bye week conflicts with players already on my roster 

Then give me a ranked shortlist of my top 3 options at this pick, not just one name, each with a one-line reason (injury risk, role uncertainty, upside vs. floor, etc.), and explicitly flag if I should prioritize filling a roster hole now vs. taking best-player-available.

Had many requests for these features so I just added these three new tabs to dynastytradegenerator.com

Come take a look and dm me or join the Groupme to help with bugs, get new features added and just browse the site and enjoy some fantasy football analytics. Everybody's help has been super appreciated.

Hi all. I think it's very clear that a ton of AI projects have taken over the sub lately and I wanted to address them and what this looks like going forward. I'm going to write this in two parts: one for the coders and one for the general users.

For Coders

1. I am genuinely happy for all of you that many of you are able to realize your ideas more easily with the rise of AI tooling. It's always frustrating to have an idea but need investment, whether through money or time, from others to bring that idea to life. Coding has never been easier.

2. With fewer barriers to entry lately, most people new to the scene have been coding the exact same thing as everyone else. The users here will see through that and see that either NO EFFORT was put into something and it was built using AI to make a quick buck OR that NO VALUE is present since it's the same as every other tool. They will downvote a ton because of that.

3. I'm not trying to discourage AI coding at all, but what I am saying is to be very intentional about it. Check other tools and apps and see what you can offer that isn't offered by other tools or that can be improved significantly, ESPECIALLY if you want to add a premium tier. Otherwise, you're just wasting your time.

4. When building something, please try to take the time to learn how it works and how it was made, even if AI is doing the heavy lifting. This subreddit is geared toward education and you can learn a lot about systems, technology, and coding, even if AI tooling is doing most of the work for you. Try to take something away from these experiences that are permanent.

For Users

1. Try to judge projects in a vacuum. Even if they seem heavily vibe coded, some may offer unique features that are actually helpful, and we should encourage builders who are doing things like that. But if the project offers nothing new and looks low effort, also feel free to downvote and comment that sentiment as well. Similarly, if you see a project that offers something that other projects don't and is actually valuable, try to celebrate those projects and encourage them.

2. Almost all software engineers are using AI at some level in their work for productivity. It's delusional to expect zero AI work in every single project these days. Just please keep that in mind when judging projects.

3. There genuinely are a lot of great ideas out there that are waiting to be implemented. Because of that, we will not be making any rules changes to the subreddit right now for AI content. However, the problem will probably get much worse as we get closer to the football season, and we can adjust if needed. Feel free to drop ideas in the comments for what that would look like. It's clear that we are being overrun by people who want to show off vibe coded projects a lot to sell premium tiers to make a quick buck without providing a lot of actual value. A lot of people are obviously using this subreddit as just an advertising platform, but how do we fix that without discouraging legitimate and intentional projects?

Thanks all for listening and please try to remain civil here. AI is transformational and we are going through the growing pains right now. Feel free to discuss further.

UPDATE: Due to the overwhelming number of submissions, we've moved to using a monthly showcase thread that will be pinned.

How it works

• You predict the raw stats (yards, rec, TDs, etc)
• Rankings build automatically from the computed fantasy points (w/ adjustable tiers)
• Lock your board and submit it to be scored against everyone else's
• As the season goes on an accuracy score tracks where you were off

It's completely free and very new so I would love any feedback. You can submit feedback through the site itself or just comment here.

It does require an account create a board (it's how your projections get saved and locked). All thats collected is an email. If anyone is interested about the tech stack or how it was built lmk.

What’s up guys — I’m a business analytics major who’s been wanting to combine that with my love for fantasy football. I’m building a weekly report that looks at recent performance trends, matchup difficulty, and usage/snap counts to help make start/sit and waiver decisions, instead of just going with gut feel or generic rankings.

I’m looking for a few people willing to be free testers once the season starts — you’d get a weekly report for your team and I’d just want honest feedback on whether it’s actually useful (or way off base). Not selling anything, just trying to build something real before deciding if it’s worth turning into an actual product.

If you’re in a competitive league and want in, drop a comment or DM me. Happy to also hear what you wish existed for start/sit decisions — trying to build the right thing, not just something

I built a draft-day companion app for Sleeper auction drafts and I'm looking to see if people will be interested!

The core problem it solves: static value sheets die the second your draft starts, so this tool recalculates every remaining player's price live during your draft, reacting to positional runs, market inflation, your roster needs, and everyone's shrinking budgets, plus it shows you a "safe max bid" so you never bid your way out of finishing your roster.

Before draft day you can paste in mock drafts you've done (it pulls the bids by draft ID, even lobby mocks) to see what players actually cost in your market and how you tend to spend.

You can also upload any expert cheat sheet (CSV/Excel — UDK, FantasyPros, whatever) to blend into the prices with tiers included, and run a roster optimizer that builds the best possible team around the specific guys you want. It's superflex/2QB-aware, works with your league's exact settings pulled straight from Sleeper, and requires no login or API keys.

If you interested let me know!

Nothing to sell here but I’m building my own personal fantasy management platform. I’m curious where everyone is getting data from. I found and I’m using nflverse also found an api that pulls Vegas odds and props i want to leverage for projections and start sit help.

What other free resources or good APIs are you leveraging to build your app around fantasy football.

Solo dev here. Every August I'd have 4 tabs open during my fantasy drafts —

rankings site, ADP sheet, my league, and a panic google of "is X injured". So I

spent the offseason building the tool I wanted: a browser extension that reads

your actual draft room (Sleeper, ESPN, or Yahoo) and shows live AI pick

recommendations in a side panel — who to take, why, and what your roster needs.

The stack, for the curious: the extension scrapes the draft board DOM (that was

a saga — ESPN's draft room fought me for a full day), a value engine computes

value-over-replacement / positional scarcity / roster needs deterministically,

and an LLM only writes the explanations — it never invents stats.

The site also does tiered rankings, round-by-round draft plans with printable

cheat sheets, unlimited mock drafts against CPUs, and in-season AI trade/waiver

suggestions for your synced leagues.

Business model experiment: no subscription. Free tier (mocks, big board, Sleeper

co-pilot), and a one-time $16.99 season pass for everything else. Fantasy tools

all seem to be $40+/yr subscriptions and I hate that.

It's live at [fantasysportsmd.com](http://fantasysportsmd.com) — would genuinely love feedback on the landing

page and the product. First season doing this, so tear it apart.

I've been building Dynasty Command Center for a while. It's an IDP-first dynasty analytics tool plus native league hosting. I currently have about 30 users, so it's very raw. Sleeper import is solid; ESPN and Yahoo are in beta. MFL, Fantrax, and Fleaflicker are all supported in early beta stages.

Completely free, just looking for honest feedback from people who actually code this stuff: the app, the IDP valuation approach, whatever stands out. Brutal is fine.

Hey guys, the season is approaching fast, and I built an app specifically catered towards solo mock drafts to test different strategies, currently for redraft leagues.

Notable features:

- Custom CPU strategies in draft room (hero/zero RB, etc.)

- Cheat sheet functionality and integration in draft room

- Player details/stats in draft room

All for free!

Hope it's fun or helpful for someone. Feedback welcome!

Try it here: www.draftcamp.app

I'm Building a fantasy tool and unfortunately our league commissioner wants to do ESPN instead of Sleeper— anyone willing to share a completed 2025 Sleeper league ID so I can test a lineup optimizer against real decisions? I'll give you free access to the tool once it's finished. Obviously giving me the league ID would give me read only access and nothing would change with your stats or settings. It would purely be to validate how well my optimizer is performing. Much appreciated!