Citizen
Other Open Roles
Prior Listings
Engineer, Machine Learning
Engineer, Machine Learning
About Citizen
Citizen is the No. 1 public safety app in the U.S., with a mission to make the world a safer place. Citizen provides 911 alerts so people can use their phones to keep themselves, and the people and places they love, safe. Citizen has notified people to evacuate burning buildings, deterred school buses from nearby terrorist attacks, and led to the rescue of kidnapped children and missing people.
Citizen’s 911 alerts are accompanied by live stories, real-time updates, and user-generated content so app users never have to wonder why there are helicopters overhead or fire engines passing by. We act fast, break news, and give people the immediate information they need to stay safe. And we’re just getting started.
Already relied on by millions of people every day, Citizen will expand even further across the United States this year to keep more users safe and informed. We’re looking for hardworking, mission-driven individuals to help bring Citizen to hundreds of cities nationwide.
Citizen is backed by Sequoia Capital, 8VC, Founders Fund, Goodwater Capital, and Greycroft and has raised tens of millions in VC funding.
Our Challenges
- Scaling: We have one of the fastest-growing organic user bases in NYC, and have expanded to multiple other cities. We are focused on the nationwide launch and the need to support that scale. A Citizen international launch will follow.
- Bursting: We designed our infrastructure to scale without notice in case of a spontaneous incident where we need to inform our entire user base. On significant events, we see over a million simultaneously connected clients and their associated live streams. The core systems need to be able to efficiently support these traffic patterns and continue to scale to millions of more users in the future.
- Machine learning: We process thousands of hours of audio every day looking for incidents that impact our users’ safety. To do this at scale, we’ve built ML models for audio analysis and targeting using the current state of the art from academia.
- Analytics: We want to alert users to the incidents that matter to them, in a way that scales across different geographic densities and demographics.
- Mobile video streaming: Our app will ingest high-quality video at low-latency, transcode, and redistribute the video to external media outlets seamlessly.
- Radio hardware: We build our own software-defined radio-based devices to consume all radio dispatch in every major city, whether analog or digital.
Our Stack - languages and technologies we use and teach
- Mobile: Swift (iOS), Kotlin (Android)
- Web: React.js, TypeScript
- Services: Go for transactional systems; Python for analytical systems
- Datastores: Cassandra, MySQL, Redis, Google PubSub
- Infrastructure: Kubernetes on Google Cloud
Role Description
- Develop a deep neural network for audio flagging to improve operational efficiency
- Develop a Churn model to help determine when a customer is about to churn from Citizen
- Help determine how users are targeted for notifications
- Design feed ranking algorithms to improve business objects, including: Shares, Sign-ups, etc.
- Develop models for moderating video content (TV/Games, No content, etc.)
- Select best thumbnails from a list of videos and ranking videos within an incident
Preferred Qualifications
- Computer Science degree or Machine Learning related degree; or equivalent work experience in the field
- Good theoretical grounding in core Machine Learning concepts and techniques
- Ability to reason about and grasp the intuition behind fundamental principles of Linear Algebra, Statistics, Probability
- Experience with a number of ML techniques and frameworks, e.g. data discretization, normalization, sampling, linear regression, decision trees, SVMs, deep neural networks, etc
- Familiarity with one or more DL software frameworks such as TensorFlow, PyTorch
- 3+ years experience leading and delivering effective ML solutions for large scale production use cases
Citizen offers a competitive benefits package including medical, dental, vision, flexible spending accounts, unlimited PTO, company holidays, stock options, commuter benefits, lunch daily, weekly team dinners, regular team outings, guest speakers, and lots more!
Citizen is proud to be an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all.