Carl Barrdahl, Developer in Stockholm, Sweden
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Carl Barrdahl

Verified Expert  in Engineering

Full-stack Developer

Stockholm, Sweden
Toptal Member Since
August 15, 2022

Carl is a full-stack developer with nearly a decade of experience building applications and dashboards in React and Node.js. He has a solid background in performing API integrations for services such as Stripe and Shopify. Skilled in several technologies, programming languages, and frameworks, Carl is a quick and efficient professional, a good communicator, interested in customer journeys, and with some experience in Figma.


Zephyr Valley AB
React, Node.js, JavaScript, Ethereum, Chakra UI, Solidity, Next.js, REST APIs...
Next.js, React, Bulma, Node.js, GraphQL, Facebook Pixel, REST APIs, JavaScript...
Evolve Technologies
React, MongoDB, GraphQL, JavaScript, REST APIs, Node.js...




Preferred Environment

React, Node.js, Next.js, GraphQL, SQL, Ethereum, tRPC, Prisma, Chakra UI, TypeScript

The most amazing...

...platform I've built connects GitHub APIs with Ethereum smart contracts enabling the funding of open-source projects and issues.

Work Experience

Senior Full-stack Developer

2020 - PRESENT
Zephyr Valley AB
  • Built a website for a decentralized autonomous organization (DAO) using Next.js and Chakra UI based on Figma designs. Also, connected Web3.js and blockchain wallet with RainbowKit and Wagmi.
  • Integrated an Ethereum smart contract in a Next.js (React) front end.
  • Developed various prototypes with Next.js and Chakra UI and explored technologies such as GraphQL, Prisma, RPC, Supabase, Vercel, PostgreSQL, and more.
Technologies: React, Node.js, JavaScript, Ethereum, Chakra UI, Solidity, Next.js, REST APIs, Vercel, Prisma, Minimum Viable Product (MVP), TypeScript, Full-stack, Stripe, Full-stack Development, Cryptocurrency Wallets, React Query, Gatsby, HTML5, Front-end, APIs

Full-stack Developer

2018 - 2019
  • Developed a brand new front end for a company in the real estate business. Worked closely with one graphic designer, one UX designer, and a back-end team of five in an Agile environment using Next.js, Apollo, GraphQL, and Jira for project management.
  • Created an embeddable widget for customer websites to collect insights from user behavior to target ads.
  • Built a marketing campaign configurator with multiple steps and forms.
Technologies: Next.js, React, Bulma, Node.js, GraphQL, Facebook Pixel, REST APIs, JavaScript, Full-stack, Full-stack Development, Front-end, APIs

Full-stack Developer

2018 - 2019
Evolve Technologies
  • Worked with two developers and one UI/UX designer to build an e-health platform for video calls with a mobile app and admin dashboard using Serverless on AWS, MongoDB, and BankID.
  • Created a dashboard for an emergency response center showing the vehicles on a map in real-time using React and WebSockets.
  • Built a progressive web app for IKEA Family to be used to sign in attendees for their internal events with a QR scanner to read tickets and offline support.
Technologies: React, MongoDB, GraphQL, JavaScript, REST APIs, Node.js, Minimum Viable Product (MVP), TypeScript, Full-stack, Full-stack Development, Front-end, APIs

Full-stack Developer

2017 - 2018
  • Created real-time components in React and Redux used to manage orders from the different stations in the restaurant. Integrated push notifications for customer communications in the app.
  • Created an IoT platform with real-time data visualization components in React and Redux. Deployed to AWS for high availability and low latency real-time communications and integrated with Elasticsearch for advanced search queries.
  • Developed an online real-time multiplayer mobile game in React Native and GameSparks as back end, push notifications to increase player engagement and payment using Swish (Swedish mobile bank app) integration.
  • Built a React Native app for tracking the quality of motocross tracks using Google Cloud and Firebase on the back end.
Technologies: React, Next.js, Elasticsearch, Redux, AWS IoT, Push Notifications, Firebase, GameSparks, Bootstrap, REST APIs, JavaScript, Node.js, Minimum Viable Product (MVP), Full-stack, Full-stack Development, Front-end, APIs

Front-end Developer

2015 - 2016
Telenor Connexion
  • Created high-quality data visualizing components in React and Redux.
  • Deployed to AWS for high availability and low latency real-time communications.
  • Integrated with Elasticsearch for advanced search queries.
Technologies: React, AWS IoT, Material UI, REST APIs, JavaScript, Node.js, Front-end, APIs


A food truck point-of-sale system where customers can discover nearby food trucks and place orders for pickup.

It was built with Next.js and Chakra-UI. The back end is connected to tRPC and Prisma to connect to a Postgres database hosted on Supabase.

Stripe is used to connect merchants and Mapbox to display the trucks on a map with a detailed information overlay.

Gitwork is a side project where GitHub issues can be funded with tokens. A developer can create a pull request (PR) on GitHub by tagging the problem to close.

When the PR has been merged, the developer can go to a page to claim the bounty. A GitHub API verifies if the signed-in user has, in fact, closed the issue and generates a signature for the user. This signature is sent to the smart contract to claim the bounty.

Kaly | Web3 Calendar
Kaly is a decentralized calendar and scheduling app. It's built with Next.js, Chakra UI, Ceramic, FullCalendar, and iCal specifications. I built it as a prototype to explore how DAOs could have shared calendars that users can subscribe to and where each user account is in control of their data.

Code and screenshots can be found at:

Atoll IDO
An IDO launchpad built for Defi & Cross-Chain Interoperability Hackathon event.

The application was built with React, Next.js, Chakra UI, and Ethers.js. Stripe Identity was used for KYC, so only verified identities were allowed.

Lizard Pay
Pay Stripe invoices with USDC.

Built with React, Next.js, Stripe, RainbowKit, and Wagmi and deployed to Vercel. The customer connects their Stripe account, and their invoices are listed, and a payment link can be copied to share with clients to connect their wallet and transfer to the specified wallet address.

A dashboard was built to connect USDC transfers to matching invoices.


JavaScript, GraphQL, TypeScript, HTML, CSS, HTML5, SQL, Solidity


Next.js, Tailwind CSS, Bulma, Redux, Bootstrap, Material UI


React, Node.js, Stripe, Stripe API, REST APIs, Web3.js, Stripe Connect, Stripe Connect API, iCal


Prisma, Stripe Checkout, Figma, FullCalendar, Facebook Pixel, GameSparks


Chakra UI, User Interface (UI), Minimum Viable Product (MVP), Full-stack, Full-stack Development, wagmi, React Query, Front-end, APIs, tRPC, Supabase, Ethers.js, Gatsby, Content Management Systems (CMS), iCalendar, Cryptocurrency Wallets, Lottie, Push Notifications


Blockchain, Ethereum, Vercel, Firebase, Mapbox, AWS IoT


MongoDB, SQLite, PostgreSQL, Elasticsearch


NEAR Certified Developer

NEAR University

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