Full-Time

Senior Frontend Web Engineer

Frontend Development, React

Posted on 9/24/2025

Sleeper

Sleeper

51-200 employees

Ad-free premium fantasy sports platform

Compensation Overview

$150k - $235k/yr

Remote in USA

Remote

Category
Software Engineering (1)
Required Skills
JavaScript
React.js
GraphQL
Next.js
Web Development
Requirements
  • A degree in Computer Science or equivalent experience
  • 5+ years of web development with an emphasis on frontend
  • Proven ability to develop and implement algorithms or systems in a professional setting, with strong coding skills in Javascript and strong a web technologies skillset
  • Highly proactive, with a track record of building processes from scratch and a willingness to challenge traditional risk management paradigms
  • Comfortable in fast-paced, ambiguous environments, thriving on innovation and the challenge of creating something new.
Responsibilities
  • Collaborate with designers to understand user requirements and translate them into technical specifications for the React web application.
  • Write clean, maintainable, and efficient code using React, JS, and related libraries (Tailwind, React Query, NextJS, etc.).
  • Develop reusable UI components and implement a well-structured component hierarchy for the React application.
  • Implement user interface (UI) functionality and logic using React features like state management, hooks, and server-side rendering.
  • Integrate front-end components with back-end services using APIs (RESTful or GraphQL).
  • Troubleshoot and debug complex web application issues
  • Stay up-to-date on the latest advancements in React, web development best practices, Core Web Vitals, and accessibility guidelines.

Sleeper runs a fantasy sports platform that lets users manage fantasy football leagues and bracket pools through an engaging app. It focuses on social features like in-app chat, live game watching, and intuitive design so players can communicate, react, and enjoy games together. The product works by offering premium features such as advanced draft modes and customization, all without ads, and monetizes through these paid enhancements rather than advertising. Sleeper differentiates itself from competitors by prioritizing a premium, ad-free user experience and a tight, design- and product-focused team. This approach has led to high engagement and retention, with millions of users who stay active across seasons. The goal is to connect sports fans through a social and immersive fantasy experience, providing deeper interaction and enjoyment around games while keeping the platform enjoyable and ad-free.

Company Size

51-200

Company Stage

Series C

Total Funding

$67.3M

Headquarters

San Francisco, California

Founded

2014

Simplify Jobs

Simplify's Take

What believers are saying

  • Kalshi integration boosts engagement for 10 million users pre-Super Bowl.
  • High retention from live play-by-plays and personalized alerts.
  • $115B annualized Kalshi volume expands Sleeper's prediction markets.

What critics are saying

  • CFTC enforces against Sleeper's Kalshi sports gambling in 6-12 months.
  • PrizePicks erodes users with faster esports payouts in 12-18 months.
  • App stores ban Sleeper's prediction trading in 3-6 months.

What makes Sleeper unique

  • Sleeper provides ad-free platform with in-app chat and voice features.
  • Advanced tools enable multi-team trades and year-round league activity.
  • Esports fantasy integrates PandaScore data and League of Legends leagues.

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Benefits

Health Insurance

Unlimited Paid Time Off

401(k) Retirement Plan

Company News

Business Wire
Feb 6th, 2026
Sleeper integrates Kalshi prediction markets as platform hits $115B annualised volume

Kalshi, the world's largest prediction market, has partnered with sports app Sleeper to integrate prediction markets directly into its platform. Sleeper's 10 million users can now trade prediction markets on sports, with additional real-world event markets launching soon. The integration continues Kalshi's distribution strategy of powering prediction markets across platforms including Robinhood, Coinbase and PrizePicks. Annualised volume on Kalshi has crossed $115 billion, with Sunday's pro football championship market alone projected to exceed $800 million in trading volume. For Sleeper, the partnership expands user engagement beyond its fantasy leagues and daily fantasy sports offerings. The integration arrives ahead of the Super Bowl, allowing fans to participate in prediction markets where they already gather around sports.

INACTIVE