Available for freelance projects in Q1 2026✳︎

Crafting delightful interfaces with design and code

Welcome

Matt Castillo is a freelance design engineer based in Brooklyn, NY. He specializes in building polished software and web experiences. Most recently, Matt has partnered with companies in AI, finance, healthcare, and identity.

Additionally, Matt maintains a digital garden, an unpolished collection of notes and ideas, where he shares his thoughts on design, technology, and life.

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Index

  1. Work

    Selected products and websites

  2. Garden

    Unpolished posts, notes, and ideas

  3. About

    About this site and its author

Selected works

App Store

Bobbin · The simplest way to plan sewing projects, in your pocket

Objective

I designed and developed a sewing organizer app for sewists to plan sewing projects, organize their stash of patterns and fabrics, and find inspiration for their next make. Available now on the App Store.

Services

  • design
  • app development
  • branding
  • web development
Bobbin hero image
Bobbin is a sewing organizer app for sewists to plan sewing projects, organize their stash of patterns and fabrics, and find inspiration for their next make.
Bobbin's interface is designed to fit seamlessly into the sewing workflow, with a focus on simplicity and ease of use.
Bobbin app icon
A simple, approachable app icon designed for clarity on any device.
A microsite built with Astro to showcase the brand and features of Bobbin.
Bobbin on multiple devices
Designed for both iPhone and iPad, Bobbin allows users to fit the app perfectly into their workflow.
Bobbin brand identity
Bobbin's brand identity was designed to feel approachable to sewists at any level, with a minimal color palette and handmade aesthetic.
Bobbin collage mode on iPad
Collage Mode allows users to plan and visualize their projects before they start sewing.

kandji.io

Iru (formerly Kandji) · Better experiences for IT and InfoSec

Objective

Oversaw the design & research org in the launch of several products and creation of a new design system — which helped the company scale upmarket and increase revenue by 600%

Services

  • Product Design
  • UX research
  • Design Systems
  • Leadership
Kandji on macOS
Kandji's platform allows IT admins to manage and secure devices at scale, while providing a seamless, native software experience for end-users.
As Director of Product Design, I oversaw the creation of a new design system that would replace a legacy component library and scale with the company's growth.
Kandji Devices
This design system was leveraged across the web platform to create consistent enterprise experiences for IT and InfoSec use cases.
Kandji App Icons
As the primary designer for the end-user apps, I was also responsible for app icons and other visual assets.
Many features, like Lost Mode, needed to consider the end-to-end workflows and needs of both IT admins and end-users.
Despite being an enterprise B2B platform, the UX was designed to be intuitive for beginners and power users alike.

shippo.com

Shippo · Automating fulfillment for online merchants

Objective

I designed shipping and automation tools used by 100,000+ online merchants to streamline their fulfillment process

Services

  • design
  • development
  • UX research
Shippo hero image
Shippo helps merchants by syncing orders from their online stores and providing tools to easily fulfill and ship them.
Shippo interface design
Shippo's core product allows merchants to purchase discounted shipping labels from multiple carriers.
Automating fulfillment for online merchants
Merchants are always looking for ways to save time in their fulfillment process. A key feature that I delivered was an automation builder that applies rules to incoming orders based on certain attributes.
Shipping label creation
The platform would then automatically select the best carrier, rate, and shipping options for the order based on the automation rules.
Mobile shipping experience
Shipping can be a complex process — especially for small businesses with limited resources. Shippo's UI was designed to bring transparency and ease-of-use for merchants and their customers.
Carrier integrations
When I joined Shippo, the platform was only designed for desktop screen sizes. I was responsible for ensuring that the platform was accessible and usable on mobile devices.
User journey map
A helpful tool for identifying pain points and opportunities — I like to use User Journey Maps to build a shared understanding of the end-to-end user experience.

inrupt.com

Inrupt × Yorba · A personal & private AI chatbot

Objective

I designed and developed a prototype to demonstrate Inrupt's Solid technology for user privacy in an AI context

Services

  • design
  • development
Charlie - A personal & private AI chatbot
Charlie is a prototype demonstrating Inrupt's Solid technology for user privacy in an AI context. Users can toggle access to their personal data on or off as needed.
The onboarding experience allows users to connect their digital identity and toggle access to their data.
When access is granted, the AI chatbot securely accesses the user's data and provides personalized responses. Users can toggle access at any time.
As the design evolved, I generated mockups and components in partnership with the development team.
Evolving the visuals to create a more engaging and personal experience for the final prototype.

Full-stack expertise to bring your vision to life

IruDabbleRucaShippoLyftQuantaResetOneInrupt

Offering

After 12+ years designing and delivering software, I now work with companies as a freelance partner to ship engaging experiences with both speed and quality.

I enjoy transforming complex ideas into intuitive experiences, making me an ideal partner for B2B SaaS, fintech, developer tools, and other technical spaces.

Available for freelance projects in Q1 2026.

Let's chat

Product

  • User Interface Design
  • User Experience Design
  • Prototyping
  • User Research
  • Design Systems
  • Interaction Design

Web

  • Front-End Development
  • Framer/Webflow/Squarespace
  • CMS Implementation
  • WordPress Development
  • Shopify Development
  • React/Next.js Development

Creative

  • Brand Identity
  • Visual Design
  • Motion Design
  • Copywriting

Leadership

  • Design Leadership
  • Product Strategy
  • Design Hiring
  • Career Pathways