Steve is available for hire

Steve Johnson

Verified Expert in Engineering

System Design Developer

San Francisco, CA, United States

Toptal member since May 13, 2022

Expertise

Full-stack Web Development SaaS Back-end Developers API Dashboard Interim CTOs Artificial Intelligence LLM Prompt Engineering RAG

Bio

Steve has worked in tech for 10 years, with 8 years of full-stack startup engineering experience. He has created AI, education, recruiting, bike-sharing, marketing, and sales software that millions of people have used. Steve loves delivering digital products that unlock value and reduce costs.

Portfolio

Bosmos

Supabase, Next.js, TypeScript, Stripe, Tailwind CSS, Startups, Vibe Coding...

YourStory

Supabase, Next.js, OpenAI, Full-stack, Startups, Vibe Coding...

BeFluent

Supabase, Ionic, Android, iOS, Startups, Artificial Intelligence (AI)...

Experience

System Design - 11 years
TypeScript - 8 years
Full-stack Development - 8 years
MVP Design - 6 years
CTO - 4 years
Fractional CTO - 4 years
Supabase - 3 years
Next.js - 3 years

Preferred Environment

TypeScript, Next.js, Supabase, Startups, Artificial Intelligence (AI), MacOS

The most amazing...

...thing I've done is moving to San Francisco with no software skills and, in three years, becoming the CTO of a YC (venture-backed) startup.

Work Experience

CTO | Co-founder

2025 - 2025

Bosmos

Built a full-stack application enabling freelance matchmaking between sellers and buyers.
Reached 1,000 MAU and $40,000 ($120,000 annual projected) revenue.
Built chat, file, escrow, invoicing, fraud systems, and more.

Technologies: Supabase, Next.js, TypeScript, Stripe, Tailwind CSS, Startups, Vibe Coding, Software QA, Proof of Concept (POC), CTO, Web Development, API Integration, Claude Code, Cursor AI, AI-generated Code, Claude API, JSON, Vercel, System Architecture, Cybersecurity, Full-stack Development, APIs, Architecture, AI Tools, Codex, Dashboards, Reliability, Security, Identity Verification, Model Context Protocol (MCP), JSON REST APIs, Twilio, User Experience (UX), Accessibility, Web Accessibility, CI/CD Pipelines, E2E Testing, Testing, Front-end Development, WebSockets, Monorepos, SaaS, Technical Project Management, Agile, Scrum, Quality Assurance (QA), Payment APIs, Back-end, Authentication, Magic Link, AI-assisted Development, Databases, Minimum Viable Product (MVP), Product Management, Cloud Infrastructure, Data Management, Data Modeling, REST APIs, ChatGPT, Full-stack, Shadcn UI, LearnDash, Shadcn, Third-party APIs, Cloud Platforms, Scheduling, Real-time Systems, Message Queues, Queuing Systems, Real-time Data, Software Architecture, Scalability, Software Design, Code Auditing, Product Engineering, Web Scalability, Prototyping, Global Team Management, Product Strategy, Technical Hiring, UI Design, Product Design, Team Building, System Integration, Business Requirements, Process Mapping, Solution Design, Stakeholder Interviews, Claude, Workflow Automation, Row-level Security (RLS), API Architecture, AI Chatbots, Conversational AI

CTO | Co-founder

2023 - 2025

YourStory

Built a full web stack delivering AI-powered classroom lessons.
Reached 10,000 MAU, 50,000 ARR, 100,000 fundraised (nine million cap).
Built classroom management systems, creations, libraries, personal adaptations, visual aids, and more.

Technologies: Supabase, Next.js, OpenAI, Full-stack, Startups, Vibe Coding, Artificial Intelligence (AI), Software QA, Proof of Concept (POC), CTO, Whisper, Data Scraping, Web Scraping, Image Manipulation, Machine Learning, Recommendation Systems, Gemini, Gemini API, OpenAI API, Retrieval-augmented Generation (RAG), Prompt Engineering, Vector Databases, Agentic AI, Vercel, API Integration, Anthropic, System Architecture, Cybersecurity, Full-stack Development, APIs, Architecture, Claude, Dashboards, Reliability, Security, Identity Verification, JSON REST APIs, User Experience (UX), Accessibility, Web Accessibility, CI/CD Pipelines, E2E Testing, Testing, Front-end Development, Monorepos, AI Product Management, SaaS, Technical Project Management, Agile, Scrum, Quality Assurance (QA), Payment APIs, Back-end, Authentication, Magic Link, Agentic Engineering, Databases, Generative Artificial Intelligence (GenAI), Minimum Viable Product (MVP), Product Management, Cloud Infrastructure, Data Management, Data Modeling, AI Voice Agents, REST APIs, ChatGPT, JSON, AI Integration, Third-party APIs, Cloud Platforms, Message Queues, Queuing Systems, Real-time Data, AI Automation, Software Architecture, Large Language Models (LLMs), Scalability, Software Design, Code Auditing, AI Tools, Product Engineering, Web Scalability, Prototyping, Product Strategy, Technical Hiring, UI Design, Product Design, Team Building, System Integration, Business Requirements, Process Mapping, Solution Design, Stakeholder Interviews, Agentic RAG Systems, Workflow Automation, Row-level Security (RLS), API Architecture, AI Chatbots, Conversational AI, AI Avatars, Avatars, RAG Architecture, Scalable Vector Databases

CTO | Co-founder

2023 - 2024

BeFluent

Built web, Android, and iOS applications for AI-powered business English language learning.
Developed AI chat and AI learning exercises tailored to user interests and goals.
Built company internal tools so that company curriculum developers could tailor platform lessons.

Technologies: Supabase, Ionic, Android, iOS, Startups, Artificial Intelligence (AI), Software QA, Proof of Concept (POC), CTO, OpenAI, Vercel, API Integration, System Architecture, Cybersecurity, Full-stack Development, APIs, Architecture, Dashboards, Reliability, Security, Identity Verification, Figma, Figma to React, JSON REST APIs, User Experience (UX), Accessibility, Web Accessibility, CI/CD Pipelines, E2E Testing, Testing, Front-end Development, Desktop App, Desktop App Development, Monorepos, Application Packaging, AI Product Management, SaaS, Technical Project Management, Agile, Scrum, Quality Assurance (QA), Payment APIs, Back-end, Authentication, Magic Link, Databases, Generative Artificial Intelligence (GenAI), Minimum Viable Product (MVP), Product Management, Cloud Infrastructure, Data Management, Data Modeling, AI Voice Agents, REST APIs, ChatGPT, JSON, Full-stack, AI Integration, Third-party APIs, Cloud Platforms, Message Queues, Queuing Systems, Real-time Data, Software Architecture, Large Language Models (LLMs), Scalability, Software Design, Code Auditing, AI Tools, Product Engineering, Web Scalability, Prototyping, Global Team Management, Product Strategy, UI Design, Product Design, Team Building, System Integration, Business Requirements, Process Mapping, Solution Design, Stakeholder Interviews, Claude, Workflow Automation, Row-level Security (RLS), API Architecture

CTO

2023 - 2024

PrepFactory

Rebuilt the entire application stack: MySQL, PHP (Codeigniter), and React.
Migrated servers from Azure custom machines to standardized Docker containers.
Migrated self-hosted MySQL to modern Planetscale with auto scaling and leading security.

Technologies: PHP, MySQL, CodeIgniter, REST APIs, Startups, Software QA, System Architecture, Cybersecurity, Reliability, Security, JSON REST APIs, CI/CD Pipelines, Redis, SaaS, Technical Project Management, Quality Assurance (QA), Payment APIs, Legacy Code, Back-end, Authentication, Full-stack, Consulting, APIs, Software Architecture, Scalability, Product Engineering, Web Scalability, Prototyping, Azure

Software Engineer

2022 - 2023

PeerTeach

Created printing, scanning, and grading systems for classroom assessments.
Managed a MongoDB-to-PostgreSQL migration and database refactoring.
Created onboarding tours and implemented product analytics.

Technologies: Python, Flask, React, SQL, DevOps, MVP Design, Startups, Software QA, Computer Vision, OpenCV, System Architecture, Reliability, Security, JSON REST APIs, CI/CD Pipelines, Quality Assurance (QA), Payment APIs, Back-end, Authentication, AWS Lambda, Amazon DynamoDB, Amazon Web Services (AWS), Full-stack, APIs, Software Architecture, Global Team Management

Senior Software Engineer

2022 - 2022

SlashAuth

Created an npm package for drop-in authorization components.
Refactored an administrator portal to allow sub-administrators.
Restyled a dashboard to Figma design standards with Tailwind CSS.

Technologies: React, MVP Design, Startups, Software QA, Reliability, Security, JSON REST APIs, Quality Assurance (QA), Payment APIs, Full-stack

CTO

2020 - 2022

Quickcard

Developed a sales document editor with text, image, video, and web embeds.
Crafted a full analytics stack allowing users to track document interactions.
Engineered a client link creation process that includes selecting resources, tailoring criteria, injecting variables, and providing alternative recommendations.

Technologies: React, Node.js, TypeScript, Express.js, PostgreSQL, Full-stack Development, Software Architecture, Technical Leadership, Full-stack, User Experience (UX), User Interface (UI), Back-end, APIs, QA Automation, Leadership, Architecture, CTO, Amazon Web Services (AWS), Front-end, Software Engineering, SQL, MVP Design, Startups, Software QA, System Architecture, Monday.com, Figma, Figma to React, CRM, Customer Relationship Management (CRM), JSON REST APIs, CI/CD Pipelines, WebSockets, Technical Project Management, Automated Testing, Playwright, Quality Assurance (QA), Test Automation, Authentication, Real-time Systems

Full-stack Engineer

2019 - 2020

Studio Corsair

Created a performance metric dashboard aggregating data from Google Ads, Google Analytics, Facebook Ads, and Shopify APIs.
Engineered a cost-per-acquisition table breaking down costs by customer location.
Built a Bash shell script to streamline the creation of version release notes.

Technologies: PostgreSQL, TypeScript, Node.js, Express.js, QA Automation, Startups, Software QA, Shopify, Financial UX, JSON REST APIs, Automated Testing, Quality Assurance (QA), Test Automation, Back-end, Authentication, Full-stack

Front-end Engineer

2019 - 2019

PrepFactory

Created a calendar application with a drag and drop interface.
Engineered a scientific calculator and question-overlay whiteboard.
Developed a teacher onboarding flow with animations.

Technologies: JavaScript, React, CSS, HTML, Leadership, Startups, Software QA, JSON REST APIs, MySQL

Software Engineer

2019 - 2019

LINKA Technologies

Created a customer onboarding automation system with Shopify, Mailchimp, Typeform.io, HelloSign, HubSpot, Stripe, and Zendesk webhooks and APIs.
Integrated Authorize.net's payment support into back-end payment infrastructure.
Migrated payment systems to comply with Stripe Strong Customer Authentication (SCA).

Technologies: MongoDB, JavaScript, Node.js, Android, Webhooks, Leadership, Mobile, NestJS, Startups, Software QA, Google Maps API, JSON REST APIs, Twilio, Legacy Code, Amazon Web Services (AWS), Full-stack, Scheduling, Google Maps, Java

Experience

Freelance Marketplace

A web application for digital freelancers connecting with buyers. I built chat, file, escrow, messaging, and project management tools and worked with the business co-founder and designers. I developed the MVP and had revenue in one month.

AI and K-12 Education Startup

A full web application stack for students, teachers, and administrators. I developed AI-powered tools for K-12 instruction, including AI characters, lesson libraries, personalizations, and classroom oversight features. I built the whole technology stack with a business co-founder and one other full-stack engineer.

AI and English Learning Startup

Web and mobile apps for AI-powered English language learning. I built the whole stack, including AI chat, customized exercises, progress tracking, and meeting tools. I worked directly with the business cofounder, designer, and curriculum developer.

Tutoring Application

https://www.prepfactory.com/

I rebuilt the entire application stack and orchestrated a React front end for a tutoring service. I built an onboarding system that guided tutors through their web views. I also created a scientific calculator, a whiteboard overlay, and a scheduling system in those views.

Peer Tutoring App

http://www.peerteach.org

A Python and React education application. I coordinated peer tutoring activity between students in K-12 schools, allowing teacher and classroom-driven activity. I built the full stack with one other developer. It's a pre-seed startup out of Stanford Phd with industry-leading investors.

Sales Deck Web App

Built a document editor, a send process, and resource management views. I also created analytics and integration systems. As a software engineering generalist, I worked on everything through the front and back end.

Marketing Analytics

https://www.studiocorsair.com/rubix-insights

I developed a TypeScript application for analyzing digital marketing activity for online stores. I built out views that took data from Google Ads, Google Analytics, Facebook Ads, and Shopify APIs. This data was divided into high-level insights and actionable items to improve marketing effectiveness.

Bike Share Software

https://www.linkalock.com/

Created software to manage bike-share hardware. We created systems to manage payments, monitor bicycle location and status, and analyze customer activity. Migrating to new hardware devices and back-end tools, we took this startup to the next level of operation.

Education

2012 - 2016

Bachelor's Degree in Engineering

University of Maryland - College Park, MD, USA

Skills

Libraries/APIs

React, Node.js, REST APIs, Claude API, OpenAI API, Stripe, Google Maps API, OpenCV, Vue, Playwright, Google Maps

Tools

Claude, ChatGPT, Whisper, Claude Code, Codex, Slack, WebStorm, Figma, Amazon Cognito, Shadcn UI, Prisma, LearnDash, Shadcn

Languages

TypeScript, JavaScript, CSS, HTML, Python, SQL, PHP, Java

Frameworks

Next.js, Tailwind CSS, Express.js, Ionic, Flask, CodeIgniter, NestJS, Electron, Svelte, React Native

Paradigms

E2E Testing, Testing, Automation, API Architecture, DevOps, Automated Testing, Test Automation, Real-time Systems, Model Context Protocol (MCP), Desktop App Development, Agile, Scrum, HIPAA Compliance

Platforms

Amazon Web Services (AWS), Vercel, Microsoft, Twilio, MacOS, AWS Lambda, WordPress, Android, Mobile, iOS, Shopify, Linux, Windows, Azure

Storage

PostgreSQL, JSON, Databases, MongoDB, MySQL, Amazon DynamoDB, Redis

Industry Expertise

Cybersecurity

Other

System Design, Full-stack, Full-stack Development, Software QA, Software Architecture, Technical Leadership, Back-end, APIs, Architecture, CTO, Supabase, Artificial Intelligence (AI), Large Language Models (LLMs), Web Development, API Integration, Retrieval-augmented Generation (RAG), Prompt Engineering, Agentic AI, AI Tools, Dashboards, Reliability, Security, JSON REST APIs, Front-end Development, SaaS, Technical Project Management, Quality Assurance (QA), Payment APIs, Authentication, Magic Link, AI-assisted Development, Generative Artificial Intelligence (GenAI), Minimum Viable Product (MVP), Product Management, AI Integration, Third-party APIs, Cloud Platforms, AI Automation, Scalability, Software Design, Code Auditing, Product Engineering, Web Scalability, Prototyping, Global Team Management, Product Strategy, System Integration, Business Requirements, Process Mapping, Solution Design, Workflow Automation, Row-level Security (RLS), AI Chatbots, Conversational AI, User Experience (UX), User Interface (UI), Webhooks, QA Automation, Leadership, Front-end, Software Engineering, MVP Design, Engineering, OpenAI, Startups, Vibe Coding, Proof of Concept (POC), Gemini, Gemini API, Cursor AI, AI-generated Code, Vector Databases, Anthropic, System Architecture, Financial UX, CRM, Customer Relationship Management (CRM), Accessibility, Web Accessibility, CI/CD Pipelines, WebSockets, Monorepos, AI Product Management, Fractional CTO, Legacy Code, Agentic Engineering, Cloud Infrastructure, Data Management, Data Modeling, AI Voice Agents, Scheduling, Message Queues, Queuing Systems, Real-time Data, Consulting, Technical Hiring, UI Design, Product Design, Team Building, Stakeholder Interviews, Agentic RAG Systems, AI Avatars, Avatars, RAG Architecture, Scalable Vector Databases, Entrepreneurship, Data Scraping, Web Scraping, Image Manipulation, Machine Learning, Recommendation Systems, Computer Vision, Monday.com, Identity Verification, Figma to React, Desktop App, Application Packaging, HIPAA, Railway, AI Model Training

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