I build open source tools for exploring public data — and teach others to do the same.

Ari is a consummate professional. He is a true team player, and a very talented software developer and data scientist. Most importantly, he’s a fantastic teacher and mentor, able to communicate complex software and data science concepts to anyone from entry level analysts to senior executives. He is a lifelong learner who is constantly upskilling himself on the latest packages and libraries. He will be a great addition to any software development / data science team that needs a “Swiss army knife” who can do it all.

Ari is one of the best teachers/ trainers of coding languages (and in general) that I have worked with. He has a knack for breaking down complex things in a way that is intuitive, and helps people understand the 'why' behind various things, beyond just the 'what'. I have learned immensely from working with Ari on both project-based work and more formal coding trainings and have benefitted greatly from doing so. Working with Ari is a smooth process, he communicates well, and can do a great job of connecting business needs to technical/ coding/ software needs and requirements, effectively solving a variety of problems. I would wholeheartedly recommend Ari to anyone looking for someone with highly experienced coding/software development skills, an extremely friendly and professional demeanor, and a knack for teaching and imparting wisdom to those around them.

Ari is the best mentor one could ask for while learning both R and general software development in a professional context. Before I worked with him, I had only one college semester of R under my belt. Now I’ve written an R package we actively use at MarketBridge to deliver valuable insights to our clients. This would not have been possible without Ari’s guidance and support. He is an excellent teacher who doesn’t tell you the solution, but helps you find it on your own. He is so deeply knowledgeable about the world of R that I found myself leaving our discussions with not just the answers to my questions, but a wealth of resources and far deeper understanding of the underlying behavior of my code. Ari’s experience in software development gave me excellent guidance through his comments toward more readable, more efficient, and less error-prone code. I wholeheartedly endorse him for any work regarding R or software development, particularly in the context of the data engineering necessary for analysis and statistical modeling.

Ari is both a gifted teacher and a very insightful programmer -- attributes you don't always find strongly within the same person! He developed a clear plan to advance the R programming skills of our group and boosted our overall competency to the degree he projected in our SOI. In short, his vision matches execution, and he has the skills, insight and experience needed to succeed as a statistical consultant. Thank you Ari!

Ari is fun to work with, intelligent, and a solid software engineer. Ari took on the challenge of making the HubPages Q&A service better. I was very impressed by Ari's passion for the problem, his drive to find patterns in the Q&A analytics, and his ideas for improving the service. I believe that Ari will be a great addition to any software team.

Ari, who championed the Question and Answer feature on HubPages.com, did so much more than his "Software Engineer" title suggests. In addition to heading up initiatives for new features that improved Q&A on our site, he went the extra mile to design reports to make it easy to analyze their efficacy. It was great to work with someone who, in addition to building things, really made sure they mattered and made the impact they were intended to make. I hope I will have the opportunity to work with him again in the future!

Ari is a great communicator. Compared to other software engineers whom I've worked with, he stands out because he loves to write reports and visualize data. He worked on several projects while at HubPages, but perhaps the most significant was a system for notifying users of interesting events on the site. The scalable, adaptive system notified users via email and live notifications. It has greatly improved user engagement on HubPages.

Ari is extremely knowledgeable, detailed oriented and very nice person as well as professional to work with. He has helped me lot with my R projects. He is quick and smart. I can safely say he is an expert in teaching. I would highly recommend him.

Ari effectively balances the level of his explanations with the knowledge of his clients, be they beginners or professionals alike. More importantly he really understands his client's problems and supports others to achieve successful outcomes through a variety of channels. I did his online courses as well as a one to one session online. He organized and explained everything in advance to ensure that the session can start on time, and the live online session was a great success. His professionalism, work ethics and enthusiasm are exemplary, his knowledge is extensive, and above all his personable and kind manner set him entirely apart. I would be more than happy to work with Ari again.

Ari Lamstein recently conducted his workshop Mapping Open Data in R for the Berkeley R Meetup at U.C. Berkeley. The workshop was a tremendous.... Ari is a highly skilled and effective presenter. He is knowledgeable, well-organized, patient, and clear! His workshop examples and supporting materials are excellent. Participants came away from the workshop with the basic skills necessary to start working on mapping projects on their own. The response to his workshop by participants was universally positive, several have requested a follow-up session. If you have a mapping project and need training or technical assistance, I highly recommend Ari's workshop and services for your organization.