Sr. Software Engineer- Core Services

Twilio’s platform enables businesses to seamlessly integrate modern communications into their applications. From Uber’s anonymous driver communications, to AirBnB’s host identity verification, to eHarmony's connecting matches over the phone, businesses make their communications more relevant and compelling using Twilio. All of these use cases are enabled via simple cloud APIs with on-demand global reach.

To achieve this scale, you will be building a complex distributed platform and solve problems with availability, throughput, latency as well as real-time considerations. 

Phone Numbers systems are at the core of Twilio's services. They are in the critical path of every Twilio Call or SMS and more importantly they enable our customers to scale their business globally by communicating with their customers all over the world.

Getting reliable Phone Numbers in an ever growing list of countries is the highest factor of growth for the whole company.

About the job: 

  • Develop low latency, highly available, globally distributed services in the flight path of every Voice and SMS message.
  • Create REST APIs for customers to Search, Buy and Configure millions of phone numbers across 40+ countries and growing.
  • Design and build tools to Add, Manage and Tests phone number inventory.
  • Work in a small, empowered team. Move fast - ship to prod multiple times in a 1 week sprint.
  • Own and operate production services in AWS cloud infrastructure using the latest tools, like Datadog, Rollbar, Lightstep.
  • Full stack exposure, from UI to database. Java, Python, MySQL, Php, Nginx, all on AWS.


  • Lead development of Phone Numbers products, services and tools, in Java, PHP, Python.
  • Drive quality by writing unit, functional and performance tests in a continuous delivery environment.
  • Break down requirements, estimate tasks and plan work accurately. Definition of done is Production.
  • Support development operations, building, releasing and assisting with team on-call.
  • Collaborate with other teams and mentor junior engineers. Work cross-functionally for product launches.
  • Be a leader in engineering best practices in the team and drive continuous improvement.


  • 4+ years experience building high scale, mission critical systems.
  • Prior experience as Senior Software Engineer.
  • Experience (Re)designing complex systems, spanning multiple services and teams.
  • Expert level understanding of object oriented design and data modeling.
  • Experience with large systems and complex code bases.
  • Proficiency in multiple languages.
  • True Agile mindset (XP preferred).

About us:

Twilio is proud to be an equal opportunity workplace and is an affirmative action employer. We are committed to equal opportunity regardless of race, color, ancestry, religion, gender, gender identity, parental or pregnancy status, national origin, sexual orientation, age, citizenship, marital status, disability, or Veteran status and operate in compliance with the San Francisco Fair Chance Ordinance. 

See Inside the Office of Twilio

Launched in 2008, Twilio simplifies business communication across applications—supplying developers with the highly competent tools needed to develop customer-centric phone, VoIP, and messaging systems on its global cloud API platform. From online restaurant bookings to tech support call center networks, Twilio's flexible technology lets companies construct personalized business solutions that enhance customer-service interaction and profitability.

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