Mark TellezMark Tellez

My Resume

Skills & Expertise

Work Experience

2025
2025

VoxBird AI

2025 - 2025
AI Voice Synthesis Lead
  • Developed ensemble AI models for ultra-realistic voice synthesis
  • Created voice preservation technology beyond simple cloning
  • Built systems capturing natural breaths, pauses and speaking cadence
  • Implemented voice model training pipeline with 24-48 hour turnaround
  • Supported both English and Spanish voice generation
  • Designed memorial voice preservation service for deceased loved ones
  • Created technology that outperformed ElevenLabs for personalized voices
2025
2024

Zooly AI

2024 - 2025
Sr. Web Developer & Voice Synthesis Lead
  • Led voice synthesis team replicating celebrity voices (Snoop Dogg, 50 Cent, Cardi B, etc.)
  • Created "AI or Not?" testing system with feedback loop
  • Developed custom tuning system for ElevenLabs integration
  • Implemented parameter optimization algorithms
  • Built custom post-processing filters
  • Used React/JavaScript/TailwindCSS/AWS stack
2022
2020

DevmentorLive

2020 - 2022
Founder & Consultant
  • Built biogas system and solar-powered AI Box with RTX 4090s
  • Developed medical AI models outperforming 2018-2019 research papers
  • Created Text-To-Speech model with GANs/Transformers
  • Balanced tech work with rural farming lifestyle
  • ReactJS/TypeScript/NextJS/TailwindCSS/MongoDB expertise
  • Trained game-playing AI agents
  • Maintained mentorship relationships from Codementor
2020
2016

ReactU YouTube

2016 - 2020
Content Creator & Educator
  • 33,000 subscribers with $7k monthly revenue
  • Created educational content on JavaScript/React ecosystem
  • Pioneered technical education from Mexico City
  • Developed effective teaching methodologies
  • Transitioned to machine learning/artificial intelligence
2016
2015

Uber

2015 - 2016
PostgreSQL Expert (Contract)
  • PostgreSQL to MongoDB/MySQL migration
  • Developed database transition pipelines
  • Ensured data integrity during migrations
  • ReactJS career pivot after contract
  • Bridged sailing sabbatical and tech return
2020
2014

Codementor

2014 - 2020
Senior Developer & Mentor
  • Earned nearly 500 five-star reviews from clients worldwide
  • Helped thousands of developers with Ruby on Rails, ReactJS, and JavaScript
  • Developed a reputation for exceeding client expectations
  • Gained deep insights into consulting business management
  • Transitioned to entrepreneurship with DevmentorLive
  • Worked with diverse clients across industries and technical backgrounds
2012
2006

Various Startups

2006 - 2012
Ruby on Rails Developer
  • Built multiple e-commerce platforms
  • Developed WoW-competitive community system
  • Lived intense startup lifestyle in SF/LA
  • Mastered Ruby on Rails capabilities
  • Learned business/marketing essentials
  • Work-hard-play-hard lifestyle balance
2005
2005

GEICO

2005 - 2005
Backend Software Engineer (Contract)
  • Developed SOAP interfaces for COBOL/DB2 systems
  • Created Ruby automation scripts for interface development
  • Worked with legacy database systems
  • Trained offshore replacements during transition
  • Maintained systems during offshoring process
2006
2005

YouTube

2005 - 2006
Web Developer (Contract)
  • Developed YouTube's original comment system
  • Worked with PERL and Ruby during explosive growth
  • Adapted open source Bulletin Board systems
  • Learned scaling principles from senior engineers
  • Pivoted career focus to Ruby development
2005
2004

Callaway Golf

2004 - 2005
ASP.NET Developer
  • Maintained MySQL database systems for the e-commerce platform
  • Developed stored procedures to efficiently manage the large product catalog
  • Optimized complex queries for inventory management and order processing
  • Built ASP.NET components for the online store's shopping experience
  • Integrated merchant account services for secure payment processing
  • Developed backend services to manage the extensive product catalog
  • Introduced to Ruby/LISP by Jim Weirich
  • Pivoted to Ruby on Rails development
2005
2003

UpperDeck

2003 - 2005
Software Engineer
  • Maintained PostgreSQL systems for Marvel Vs platform
  • Developed complex SQL queries/stored procedures
  • Optimized database performance through indexing
  • Built interactive UI with JavaScript/CSS
  • Implemented drag-and-drop card management
  • Created cutting-edge responsive layouts
2003
2003

X

2003 - 2003
Software Engineer (Contract)
  • Developed pre-PayPal payment system with PERL
  • Worked 60+ hour weeks in high-intensity environment
  • Experienced Elon Musk's leadership influence
  • Learned about project ephemerality in tech
  • Developed extreme work ethic standards
2003
2001

Intel

2001 - 2003
Jr. Software Engineer
  • Pioneered sports streaming for NHL/NBA
  • Led C++ COM+ to C# .NET migration
  • Developed edge streaming media components
  • Implemented content caching strategies
  • Published 4 technical articles with WroxPress

Client Reviews

"Ive known about Mark for a while through his React courses, I reached out to him to help me start architecting an app I am building as a side project. He was awesome! I got answers to alot of the areas of this project that I was unfamiliar with and we planned out a way to get the project going. Really looking forward to continuing to work with him."

Michael Thompson

Michael Thompson

"Mark has a wealth of knowledge and expertise that is hard to find. Perfect mentor in many ways: clear and concise communication, reliable and a great teacher. I highly recommend working with him if you need help."

Jelena Grimshaw

Jelena Grimshaw

"Wow, Mark has really proved himself to be an expert in many ways. Definitely worth the investment and here's why: Pros: He works really fast, gave me some really helpful tips, explained me everything through meaningful examples and even improved some parts of already existing code in a way which makes them more clean and usable. Cons: I only wish the session was longer as I am looking forward to another one :)"

Daniel Star

Daniel Star

"I've used Mark a couple times. He is awesome! I've been using Rails, etc for 7+ years but I still get hung up once in a while...Mark knows his $h!. I won't search for mentors anymore...I'll just use Mark."

Adam Stockland

Adam Stockland

"Mark really knows his code. TDIL why implementing certain react features is preferred, and how certain design decisions are more performant. Mark is an interesting coder and skilled at teaching. I recommend him to anyone."

James Anderson

James Anderson

"I usually have more conceptual questions on Codementor and Mark came in with a good idea of what it was that I was very confused about and was quick to direct me to the concepts that I was missing. We discussed ActiveRecord (pattern, not gem). What to pass in a RESTful API to reduce cognitive load When to use objects and when to use serialized IDs as function parameters."

Stephen Huh

Stephen Huh

"Mark has been helping us daily with my website for about a week now and I would confidently recommend him to any peer looking for someone who is a fast developer, strong communicator and honest worker. "

Jack Bordner

Jack Bordner

"Really great! Mark walked me through a tricky issue I was basing off of legacy code, and came up with a much more intuitive workaround I can jump off from. Both of the issues I posted for help about were solved, and I came away with a decent toolkit to deal with some performance issues in both my code and my computer."

BoucherieDev 💾

BoucherieDev 💾

"Mark is so good at JavaScript and React (and Redux). He immediately knows how to address the task at hand and then starts throwing down code. I really appreciate his positive attitude and the time he takes to walk me through the work."

Ashley

Ashley

"Mark was very helpful in debugging a React/Redux issue. He quickly isolated an issue and that helped uncover some other problems that needed attention. He also helped after the session by providing links and references to other skilled devs."

Sam

Sam

"Mark has helped me several times at this point and is always quick and knowledgeable and writes great code (despite my usual, annoying lack of A/V for my sessions). He's worth the higher price because you know he knows what he's doing! Thanks as always, Mark!"

Ashley

Ashley

"Mark is great. Not only did he solve the problem I had, but before the session began I was having trouble with my screen sharing -- and he actually paused the session and discovered the problem with my computer. Once we fixed my computer, then we started the session and he solved my problem quickly. Moreover, he's a fun guy and I would enjoy his company regardless."

Jackson Holiday Wheeler

Jackson Holiday Wheeler

"Mark understands everything very quickly and tries to make things as easy as possible for me to understand. Also answers questions effectively. Helped me understand how shopify web builder works and started building it using rails."

Masud

Masud

"Mark is a great mentor! He's super knowledgable and as a student I appreciate his ability to explain concepts clearly. I can tell he really cares about my learning and progress. He is fair and makes sure I'm getting value from my sessions. Highly recommended!"

Anonymous

Anonymous

"Mark is very knowledgable mentor and he knows how to solve any kind of technical problem. he is very passionate about React and Rails. If you want to have deep understanding of React and Rails Mark is the mentor for you!!!"

steve chek

steve chek

"Mark was very helpful we been working on a project together and he is very excited and passionate to solve problems and teach. i HIGHLY recommend Mark to anybody who wants to build a project while learning!!!"

steve chek

steve chek

"Mark was extremely helpful. Not only did he take the time to understand the problem before starting the session, he explained what he was doing and why during the session and also paused the session once it became clear that I could move forward on my own. I recommend him 100%."

Nonni

Nonni