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Case Study

Cambly Makes Learning English Interactive and On-Demand with mLab

The Cambly founders set out to create a service that could enable anyone (from anywhere) to learn English through instructive conversations with native speakers — and to do so on-demand. To facilitate platform development and grow a global business, Cambly relies on mLab to manage the growing company's database with absolute reliability.

  • After migrating from another MongoDB DBaaS solution, Cambly turned to mLab to provide the crucial database reliability and availability that could support its global business.
  • mLab provides powerful, easy-to-use monitoring and debugging tools that enable Cambly to maintain and optimize its database performance.
  • With mLab as a partner, Cambly is confident that it can scale and match more English language tutors to eager learners all around the world.
Customer Profile

Cambly provides users with instant, on-demand access to native English speakers over video chat, either through a computer or Cambly's iOS and Android apps. Language partners are available 24/7 to help Cambly's users practice English conversation skills and pronunciation. Cambly is made up of a network of thousands of worldwide tutors. Users can select individual or group instruction, which country their tutor lives in, and/or hobbies that tutor and language learner have in common.

The Challenge

Cambly's original MongoDB DBaaS provider could not provide the reliability and uptime that the rapidly growing startup needed. The company decided to search for a battle-tested DBaaS solution that could provide zero-downtime scaling.

The idea for Cambly was inspired by the personal experiences of its two founders, who traveled extensively and relished opportunities to learn foreign languages through immersive conversations with native speakers. For new language learners, these conversations are essential for building and maintaining language skills — once removed from contact with native speakers, those skills can quickly fade. Realizing this, the founders imagined an on-demand platform that would provide immersive language experiences for those who don't have access to native speakers.

Cambly: Practice English With A Native Speaker

When the Cambly team started building the platform, it wanted a simpler alternative to directly managing machines on AWS. Cambly turned to Heroku for its application platform and also wanted a managed database solution that would make day-to-day operations easier. The team was familiar with MongoDB from past experiences and initially chose another MongoDB DBaaS to power its application. With MongoDB, Cambly could take advantage of the database's flexible schema as the product evolved.

Over time, however, Cambly discovered it needed a more reliable MongoDB DBaaS provider. Most importantly, the startup was growing its worldwide userbase and could not afford downtime when scaling the database. The team decided to search for a new DBaaS solution that had a proven track record of scaling large database deployments with no downtime.


Acting on a recommendation, Cambly determined mLab could offer the reliability and monitoring tools that the growing company would need moving forward.

Cambly's co-founders knew the team at Lyft — another mLab customer. The Lyft team recommended mLab as Cambly began looking into replacements for its previous solution. Cambly selected mLab based on that endorsement and mLab's track record managing terabytes of mission-critical data for a hyper-growth startup. With mLab, Cambly had peace of mind knowing that its scalability needs would be met over the long run.

In early conversations with the mLab support team, mLab outlined its rolling node replacement process, which ensures that Cambly will be able to operate with zero downtime during maintenance and upgrade events. mLab also provides the Cambly team with useful database monitoring and debugging tools such as the Slow Query Analyzer, which analyzes slow operations and recommends indexes, and Telemetry, which offers real-time and historical database monitoring and alerts.

mLab's support team has been incredible. Whenever I talk to an mLab support person, it's clear that they've spent a lot of time thinking about what questions I'm asking. Their answers make it clear that they don't just want to close the ticket, they want to resolve the issue.

Sameer Shariff Co-Founder, Cambly


With mLab's reliability, monitoring and optimization tools, and expert support, Cambly saves considerable time and energy — allowing the growing company to concentrate on its product and business while knowing that its data is in good hands.

Cambly takes full advantage of the mLab platform: monitoring tools, backups, and support. Tapping into Telemetry and the Slow Query Analyzer, Cambly is able to identify issues as they arise and optimize its database performance.

The Telemetry tool is so useful for getting a quick picture if there's any database issue. If we're thinking about upgrading our database plan, we can easily see if we're CPU-bound, or starting to thrash from a memory perspective. We're flying blind without that. Through mLab's Telemetry tool, we have the information we need to take the correct actions.

Edgar Higgins Engineer, Cambly

Cambly also finds considerable value and reassurance in mLab's scheduled database backups. Scheduled backups protect against human error and allow the Cambly team to quickly restore its data if an error occurs. With mLab in place as its hosted database partner, Cambly has grown to have customers in more than 100 countries learning and practicing English through its application.