Skip to content
View jonaas-dev's full-sized avatar

Block or report jonaas-dev

Block user

Prevent this user from interacting with your repositories and sending you notifications. Learn more about blocking users.

You must be logged in to block users.

Content in all repositories owned by your account will be closed.
Maximum 250 characters. Please don’t include any personal information such as legal names or email addresses. Markdown is supported. This note will only be visible to you.
Report abuse

Contact GitHub support about this user’s behavior. Learn more about reporting abuse.

Report abuse
jonaas-dev/README.md

Jonathan Sánchez

Backend Lead & Engineering Manager

Python FastAPI Django PostgreSQL LinkedIn

I lead a backend team of more than six engineers and still design the systems we ship. Six years in, across two domains: edtech first, then regulated fintech.


Leading the team

Measure delivery, not activity. DORA metrics through Swarmia: how often we ship, how long a change takes to get out, how often it breaks, how fast we recover.

What I deliberately do not measure: hours logged, who is online, time at a desk. That is noise, and measuring it teaches a team to optimise the wrong thing.

Decisions get written down. RFCs and PRDs before the code, so the argument happens once and the reasoning outlives the people who had it. I built the documentation system the team works from — architecture, standards, playbooks — because a practice that lives in one person's head is not a standard.

❝ The competent programmer is fully aware of the limited size of his own skull. ❞ — Edsger W. Dijkstra, The Humble Programmer, EWD340

Technical debt is a line in the roadmap, not a complaint in a retro. Written down, prioritised against features, paid on purpose.

Review at scale. I automate the mechanical half of code review with AI, so the team spends its attention on design instead of on style.

Growing the people, not just the codebase. 1:1s, career development, hiring and onboarding, and running the workshops that unblock a team faster than answering the same question six times.

Planning and roadmap, performance, error monitoring, and keeping the bug funnel from quietly becoming a second backlog.


Building the system

Domain Stack What I work on
Fintech · current Python · Django · FastAPI · microservices · PostgreSQL · MongoDB · OpenSearch Started in compliance and KYC, now across the platform: transfer agency, portfolio management, reporting, Odoo
Edtech PHP · Yii2 · Angular · Firebase Full stack and third-party integration, including a 7.4 → 8.2 migration, a role-based access control layer, and Microsoft Teams Education

Hexagonal architecture and DDD, in production rather than in a diagram: Python and Django microservices structured by domain, integrated with external systems through queues, webhooks and OpenSearch.

A number I am proud of: test coverage on the compliance modules taken to 92%, alongside paying down the technical debt around them. Compliance is where an untested branch stops being a bug and starts being an audit finding.

Also: SQL query optimisation and data pipelines, dynamic KYC review flows driven by roles, and a Four Eyes control migrated into the monitoring process.

The domain before the framework, and a test suite you trust enough to deploy on a Friday. Software that is still cheap to change in year three is the whole objective.

❝ Program testing can be used to show the presence of bugs, but never to show their absence! ❞ — Edsger W. Dijkstra, Notes on Structured Programming, 1970

❝ The best programs are written so that computing machines can perform them quickly and so that human beings can understand them clearly. ❞ — Donald E. Knuth, Computer Programming as an Art, Turing Award lecture, 1974

Also in the toolbox

Languages Python · PHP · TypeScript
Frameworks Django · FastAPI · Yii2
Data & search PostgreSQL · MongoDB · OpenSearch
Integration Queues · webhooks · Odoo
Front Angular · Firebase

Projects

Project What it is
engineering-notes A reading notebook on engineering and technical leadership: architecture, code quality, backend, delivery and career. 63 notes that had scattered across folders and eight repositories, found and put in order.

Most of what I work on is private. This list grows as that changes rather than being padded to look longer.


❝ Simplicity is prerequisite for reliability. ❞
— Edsger W. Dijkstra, EWD498, 1975

Popular repositories Loading

  1. sql-performance sql-performance Public

    Benchmark common SQL performance patterns on PostgreSQL: warm-up, median timings and the EXPLAIN ANALYZE behind every result

    Python 1

  2. engineering-notes engineering-notes Public

    Engineering and technical-leadership notes: architecture, quality, backend, devops and career.

    Python 1

  3. jonaas-dev jonaas-dev Public

    Personal GitHub profile README