Real-Time Draft Guidance, Right Where You Draft

The rosterOS Chrome browser extension adds a live intelligence layer to your Underdog draft room, surfacing value, roster construction, and stack leverage in real time so every pick is made with conviction. It is free to use, and your draft data stays private with on-device processing.

Download Now

WHAT IT DOES

Every available player is graded with value, roster fit, and stacking upside in mind, so you can make quick decisions without sacrificing quality.

Player Grades That Match The Moment

Understand how your capital is distributed by position and avoid accidental over-commitment.

Draft Capital Tracker

Track your current construction in real time and see whether your draft is aligned with your intended archetype.

Build Advisor

Identify high-upside stack and bring-back opportunities before the board closes.

Stack Finder

Upload your exposure data and see portfolio context while you're on the clock, with CSV processing handled locally in your browser.

Exposure Context In-Draft

Run your own board inside rosterOS by uploading custom rankings and drafting to your process.

Custom Rankings Support

FAQ

  • Install the extension from the Chrome Web Store, open any Best Ball draft on Underdog Fantasy, and the overlay loads automatically. No configuration, no setup. Optionally upload your Underdog draft history CSV once from the popup to activate live portfolio tracking.

  • No. Everything runs locally in your browser. Nothing is sent to a server during your draft. The overlay is fast because it has to be. You're on the clock.

  • Yes. Upload your rankings CSV from the popup and rosterOS incorporates them into the grade model alongside ADP and projected points. You keep your edge and gain everything else on top of it.

  • Badges are quick draft signals that help you make faster, better decisions on the clock. Stack means the pick adds or strengthens correlation with players already on your roster. Push means it improves your roster construction for that point in the draft. Leverage means it helps differentiate your build from common field constructions. Value means you are getting a strong price relative to current market context. Risk flags picks that may hurt structure, correlation, or portfolio balance. Use badges as decision context, not automatic commands, and prioritize picks that align with multiple signals.

  • Export your draft history CSV from Underdog and upload it once from the extension popup. After that, every player on the board shows your real exposure percentage and average draft capital from your actual drafts. You can filter by tournament type to see where you're over or underweight in the specific field you're targeting.

  • Not yet — Superflex support is on the roadmap and coming soon. For now, RosterOS is optimized for 1-QB formats.

  • No. rosterOS is an independent product and is not affiliated with, endorsed by, or sponsored by Underdog Fantasy.

  • rosterOS runs entirely on your device and no data about you is ever sent to our servers. Your settings, uploaded draft history CSV, and a small local error log are stored in your browser's extension storage and stay there until you delete them. While you're in a draft, the extension reads the live page to power the overlay, but nothing from that session is recorded or transmitted. Once daily, the extension fetches public ADP and rankings data to stay fresh. The only external party that handles your personal data is ExtensionPay and Stripe for subscription management, which collect your email and payment details solely to process your subscription.

  • Email info@rosterOS.com and we'll get back to you.

Privacy Policy

Effective date: April 21, 2026

rosterOS is built to help you draft better while keeping control of your data in your hands. This Privacy Policy explains what data we process, how we use it, and what choices you have.

1) Scope

This policy applies to:

  • rosterOS.com
  • The rosterOS Chrome extension
  • The rosterOS data platform

2) What We Process

Draft CSV data (local processing)

  • When you upload draft CSV files, rosterOS processes them locally in your browser.
  • Draft CSV contents are not uploaded to rosterOS servers.
  • Uploaded CSV files may include player names, contest entry-fee or prize fields, and draft metadata.

Local extension/app storage

  • The extension and app may store settings and computed results locally on your device so features work across sessions.
  • Examples include uploaded CSV-derived portfolio stats, UI preferences, and optional custom rankings.

Live draft-page context (extension)

  • The extension reads in-page draft state needed to provide real-time analytics in supported Underdog draft rooms.
  • We do not use this access to collect account credentials or payment details.

Technical website/hosting data (website only)

  • On rosterOS.com, basic technical logs (such as IP address, browser type, request timestamps, and error logs) may be processed by infrastructure providers for security, uptime, and abuse prevention.

3) How We Use Data

We use processed data to:

  • Power draft analytics and portfolio insights
  • Save user preferences and improve product reliability
  • Maintain service security and performance

We do not sell personal data.

We do not share uploaded CSV contents or in-page draft content with third parties.

4) External Services and Data Sources

rosterOS may request public data files (such as ADP and rankings sources) and use standard infrastructure services required to deliver the product. Those providers may process technical request metadata under their own privacy terms.

5) Cookies and Tracking

rosterOS does not use advertising trackers in the extension experience. If essential cookies or similar technologies are used on the website for core functionality, they are limited to necessary operation and security.

6) Data Retention and Deletion

  • Locally processed draft CSV data remains under your control on your device unless you delete it.
  • You can clear extension/app local data through browser extension controls, app controls, or by uninstalling the extension.
  • Infrastructure logs are retained only as long as needed for operations, security, and legal compliance.

7) Your Choices

You can:

  • Choose whether to upload draft CSV files
  • Remove local data at any time
  • Stop processing by uninstalling the extension or discontinuing use

8) Changes To This Policy

We may update this policy from time to time. When we do, we will update the effective date at the top of this page.

9) Contact

If you have privacy questions, contact us at: info@rosterOS.com