Fantrax runs some of the deepest leagues in fantasy — multi-sport, obscure scoring, hundreds of rostered players — and it's the most versatile platform Roster Locker connects to. One value, your User Secret ID, imports every league on your account across all five sports Fantrax serves. It's a sanctioned, read-only API key — not your password. Here's the whole flow.
On this platform: see what Roster Locker does for your Fantrax leagues.
What you'll need
- Your Fantrax User Secret ID — a read-only key Fantrax generates for you on
your profile. It is not your password.
- That's it. One Secret ID covers everything.
Fantrax serves NFL, NBA, MLB, NHL, and Premier League soccer, and a single Secret ID reaches your leagues in all of them at once.
Where to find your Secret ID
- Log in to Fantrax the way you normally do.
- Go to your User Profile (your account settings).
- Find the User Secret ID field and copy the value.
That's the string you'll paste into Roster Locker. Because it's a dedicated API key rather than your login, you can read your leagues with it and nothing more — which is exactly why Fantrax provides it.
Why a Secret ID instead of a password
Fantrax offers a sanctioned external API (the same one third-party tools use), and the Secret ID is how it authorizes read-only access to your own league data. Roster Locker uses it to list your leagues and pull your rosters — it can't make transactions, set lineups, or change anything, and we never ask for your actual Fantrax password. Not storing platform passwords is a hard rule across every platform we support.
Step by step
- Pick your sports. When you create your Roster Locker account, the first
step asks which sports you play. Fantrax can serve NFL, NBA, MLB, NHL, and soccer — pick any of them.
- Find the Fantrax step. The connect flow queues one step per platform. The
Fantrax step is titled "Enter your Fantrax Secret ID" and points you to User Profile → User Secret ID, with a reminder that it's read-only, not your password.
- Paste your Secret ID and hit "Find My Leagues." Roster Locker looks up
every league on that Secret ID across all its sports in one pass — and where Fantrax exposes which team is yours, your team is detected automatically.
- Choose your active league. On the league step your leagues are grouped by
sport; pick the one you want the AI focused on first, and switch anytime from the league chip on the dashboard.
From there the AI is grounded in your actual Fantrax rosters and settings, so advice reflects your real teams — across every sport you play there.
A note on multi-sport plans
Because one Secret ID can pull leagues from five different sports at once, Roster Locker imports them against your plan's sport allowance: sports you've already connected always come in, and new sports fill any remaining slots. If you play more sports on Fantrax than your current plan covers, the app tells you which ones are waiting and offers the upgrade — nothing is lost, it's just queued.
Troubleshooting
- "No Fantrax leagues found for that Secret ID." Re-copy the value from your
User Profile — it's easy to grab a neighboring field by mistake. Make sure you copied the whole string with no leading or trailing spaces.
- A sport didn't import. That's usually the plan allowance described above,
not an error — check whether the app flagged that sport as waiting for an upgrade.
- Wrong team, or no team marked. Fantrax doesn't always expose which team is
yours through the API. If your team isn't set on a league, reach out (just reply to any Roster Locker email) and we'll help.
- Latest moves missing. Leagues re-sync on a schedule; you can pull the
newest rosters immediately with the refresh icon on the Team tab.
Play on more than one platform?
That's exactly what Roster Locker is built for — one membership across every sport and platform you play. Sleeper connects with just a username; ESPN and MyFantasyLeague by league URL; Fleaflicker by account email; and Fantasy Premier League by team ID. Guides for each are on the blog — and inside the app, every connect step has a "Need help finding this?" link that walks you through it.
One AI for every fantasy league you own.
Roster Locker covers 6 sports and 7 platforms — trade grades, start/sit calls, waiver targets and live draft help, grounded in your actual rosters and scoring settings. Founder pricing locked for life.
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