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Ruby on Rails, Elixir, React.js, GraphQL, Node.js, AWS, Redis, Spark & Scala (Data team)

The bulk of our infrastructure is dedicated to distributed processing for machine learning, powered by Apache Hadoop: Hive, Presto, and Spark. Our web app uses React on the frontend and Ruby on Rails on the backend. We’re hosted on AWS.

Blog Post on our Tech Stack

Lever uses our own open source MVC framework called Derby that syncs all data via Operational Transformation (the algorithm behind Google Docs). OT is the way we handle concurrency conflicts for any piece of data that is edited at the same time. In addition to real-time sync, OT allows us to provide a smoother UI since we can render updates on the client instantly without waiting for our backend to respond, while still guaranteeing consistency.

Lever makes extensive use of AWS, Docker, Node, Mongo, ElasticSearch, and Redis within our infrastructure. We use tools like Hubot to streamline deployments and Grafana to see what’s going on under the hood. In addition to automating all the things, we love to version them too! Our systems are all created using Terraform and Chef, working together to ensure consistency at all costs.

We have a service oriented stack deployed on AWS using containers. Most of our backend services are written in Go, with the exception of an NLP/ML service written in Python. Services talk to each other using gRPC.

Our web application is served statically from Cloudfront/S3 and is written using React. Is is a Progressive Web App, with a service worker to speed up delivery.

We integrate with third party software such as Google Drive, Calendar, Jira, GitHub, Asana, Slack. These areas are some of the most complex parts of our systems. They’re also some of the most important: integrations enable the “magic” of a user coming to Range in the morning and seeing all of their work from the previous day already gathered in one place.

We use Golang for our backend, Typescript and React for our web client, GraphQL to fetch data from our backend, and React Native for our mobile app. Direct experience with these technologies is not required.

Right now (from front to back): VueJS (ReactJS), Flask, AWS Simple Queue Service, Docker/Kubernetes, Tensorflow/PyTorch

Ruby on Rails, JavaScript (ES6), HTML+CSS, Sketch App, InVision, Pencil and Paper

Frontend: Javascript, React, Typescript, Flow, Mobx, Stylus, Redux, Reactive JS, Styled Components, Focal (our own in-house, open-sourced state management framework)

Mobile (iOS and Android): Java, OkHttp, Butterknife, Retrofit, XCode, Swift, ReactiveCocoa, ReactiveSwift, Kickstarter-Prelude, Argo, Runes, Curry

Desktop app: CoffeeScript, Electron.js, C#, F#, ReactiveUI

Internal tools: Angular, Elm, ClojureScript

Backend: Java, Scala, Python, Haskell, Lisp, Clojure, Go, C++

NLP/Research teams: sklearn, TensorFlow, PyTorch, CNN, RNN, Keras, Seq2Seq, xgboost, CRFs, nltk/spacy/OpenNLP, OpenNMT, Jupyter notebooks

Main technologies:

Ruby on Rails

HTML

CSS

Javascript

AWS SES, S3

Cloud hosted backed with AWS

PHP, Java HTML5 / CSS3, Angular, ExtJS, PostgreSQL, Docker

LAMP / LEMP, Laravel / Zend, Node.js, AWS, Redis / Memcache, Ubuntu / CentOS, MySQL / Mongo, VanillaJS, VueJS, HTML5 / CSS3, Angular / Backbone / Ember / Ionic

JavaScript/CoffeeScript, Python, Node.js, React + React Native, AWS Lambda, Spark, Kinesis, MongoDB, Redshift

ASP.NET / C# / MVC 4+ / LINQ / AJAX / JavaScript / jQuery / JSON / SQL / T-SQL / XML / XSL / XPath / XHTML / DHTML / CSS / Bootstrap / Rest / SOAP / Web Services