We design and ship mobile apps.
Fast, private, well-crafted apps for iOS, Android, and macOS, built with Flutter, plus the web apps and APIs behind them. Our own apps run in production. We also write books, and help engineering teams ship AI.
Apps
Consumer apps we design, build, and ship end to end — on the same engineering method we bring to clients. Full list at density-technology.com/apps.
Density Unit Converter
A fast, private unit & currency converter: 20 categories, hundreds of units, live daily exchange rates, a built-in calculator, and instant conversion search. No ads, no tracking, works offline.
Learn more →
CazaFacturas
A deductible-expense assistant for Mexican taxpayers. It cross-checks your bank statement against your SAT invoices (CFDI), finds the expenses still missing a receipt, and flags which are recoverable before the month closes and which the SAT will not accept.
Visit cazafacturas.mx →Books
Federico writes on engineering leadership and creative practice. Full catalog at ramallo.io/books.
The Invisible Distance
A field manual for engineering leaders running teams across borders. Why cross-border teams fail, and the system that makes them win.
Open the Valve
A guide to creative play: creativity is not a gift, it is a force anyone can open. Available now.
Abre la Válvula
The Spanish edition of Open the Valve, adapted for Latin American readers so it reads native in both languages.
Leadership
Federico founded Density Technology and has spent two decades shipping production software. He writes on building engineering teams that work across distance and hosts the PreVetted Podcast. More at ramallo.io and LinkedIn.
Engineering & AI for teams
The same team that ships our apps also partners with mid-market companies: senior engineering, and a pragmatic path to putting AI into production. Fixed-scope steps, outcomes over hours.
Web & mobile applications
We build and ship web and mobile apps end to end — Flutter for iOS, Android, and macOS, plus the web apps and APIs behind them.
AI features in your product
AI built into the product itself, the capabilities your customers will expect within twelve months.
Company OS
Agents running the operational, repeatable work inside the company, with humans owning the checkpoints.
AI Diagnostic
A fixed-scope, two-week engagement that produces a written AI transformation roadmap: capability and architecture gap analysis, a prioritized plan, and an honest read on whether AI is the right next move. Yours to keep, no obligation.
AI Implementation
A senior team takes the roadmap to production, as a single AI engineer or a full squad: architecture, build, evals, and ship, using patterns proven in production. Scoped to the plan, outcome focused.
Embedded engineering
Senior engineers from the Americas embedded into your team, US time-zone aligned, on a method refined over a decade. Zero forced replacements since 2019.
Agentic operations
We design and run agent systems for the repeatable work inside a company, with guardians for spend, security, and brand. Proven in our own company, Sellito Studio.
A decade of partnerships, not projects
Density Technology was formed in 2024, built on the founding team's decade of cross-border engineering partnerships for mid-market US companies. Clients stay because the work holds up in production and the relationships compound.
Retention, partnership, and replacement figures reflect the founding team's cross-border engagements from 2015 to 2025; Density Technology was incorporated in August 2024.
Sellito Studio
Sellito Studio is our own AI-native company: a productized website service for veterinarians in Mexico, delivered in seven days. It runs on the same agentic operating model we build for clients. We sell the model because we operate on it.
See it live
A real business running on the agentic model, in production with paying customers.
sellitostudio.com →Contact
For app collaborations, partnerships, and engagements. We reply within one business day.
17350 State Hwy 249, Ste 220 #24915
Houston, Texas 77064
United States