Rizwan Saleem, Senior Frontend Developer based in Manchester

About

Senior Frontend Developer · Horsefly Analytics · Manchester

I build production interfaces for a labour-market analytics platform, and I fix the tools that build them. Most of what I know about software I learned from the second half of that sentence: from tracing a hung build back to two overlapping edits, or a lint run that died on an unsaved file, and then proving the fix rather than asserting it.

What I Do Now

I am a Senior Frontend Developer at Horsefly Analytics in Manchester, a labour-market and workforce analytics SaaS, reporting to the CTO. I build and ship the production React, Next.js and TypeScript front end, and work across AWS, Terraform and PostgreSQL behind it.

  • Built the Horsefly Workspace product and a public Chrome extension beyond the scope of a frontend role, opening a new revenue stream.
  • Work on the AI-agent infrastructure behind the platform, integrating model calls and tool use into existing product surfaces rather than standing up a separate demo alongside them.
  • Work on streaming correctness at the LLM-UI boundary: token streaming, partial-render correctness, cancellation and recovery under real input.
  • Led the Next.js 13 → 14 upgrade across the main application.
  • Replaced public-facing nginx ingress with a private AWS VPC Link architecture, removing the public attack surface, and contributed to the platform’s annual penetration-test pass.

Before Horsefly I shipped product across payments fintech, enterprise operations software and an AI SaaS: Open Banking and a Microsoft Dynamics 365 integration for a London payments company, React and Next.js product engineering at an AI SaaS, and the Terminal Management System for Toptech Systems, operational software running real-world terminal workflows.

How I Work Upstream

My open-source record is in the packages almost every JavaScript project depends on without ever naming: magic-string, the source-manipulation layer inside Vite and Rollup; recast, the printer behind jscodeshift; eslint-plugin-import; postcss-selector-parser; knip. Nine fixes merged, six of them shipped in a published release.

The method matters more to me than the count, and it is the same every time:

  • Find it myself. Most of these I traced from a symptom in my own work rather than picking off a tracker. Where the diagnosis was someone else’s, I say so. On the FlashList scroll-position bug the diagnosis was the reporter’s, and the deterministic test that pins the measurement race was the harder half.
  • Reproduce against the published build, not against my reasoning. Every claimed output gets checked against the stock release before I file anything.
  • Verify differentially. Where a correct reference exists, I run the fix against it at scale: 136,000 comparisons against String.prototype.replace for the most recent magic-string fix, 32,902 disagreeing before and zero after; 20,880 generated operation sequences for a hasChanged() regression; 5,076 generated inputs for recast’s print-parse identity.
  • Disclose what the fix costs. If a change alters an existing test expectation, or leaves a related problem untouched, that goes in the pull request body rather than waiting for a reviewer to find it.
  • State release status exactly. Merged on GitHub is not shipped to users. I check the merge commit is contained in a real tag and that the version is published, and I cite that version.

A bug report is a claim. A reproduction is evidence. A differential run against a reference implementation is a proof, and it is usually cheaper to build than the argument you would otherwise have in review.

Peer Review & Appointments

Reviewing other people’s artifacts is the same discipline pointed outwards: does the thing actually run, and does it produce what the paper says it produces?

EuroSys 2027
Artifact Evaluation Committee, ACM SIGOPS
USENIX ATC ’26
Artifact Evaluation Committee
CGO 2027
Artifact Evaluation Committee, ACM/IEEE
Journal of Open Source Software
Reviewer: Data Science, AI & Machine Learning track
ReScience C
Reviewer: computational replication
Journal of Open Research Software
Peer reviewer, Ubiquity Press
Innovate UK
Expert Assessor, UKRI

Writing & Teaching

I write and make videos about software engineering, AI agents and cloud infrastructure on dev.to, Medium and YouTube. The material I care most about is the unglamorous half: how to reproduce a bug you cannot see, how to tell a real fix from a plausible one, and what it takes to move an AI feature from demo to dependable inside a real operational workflow.

Background

  • MSc Computer Science, Manchester Metropolitan University
  • BE Mechatronics Engineering, SZABIST
  • AWS Certified Solutions Architect
  • Cyber Runway Launch, cohort alumnus of the DSIT-funded UK cyber accelerator delivered by Plexal

The route here was not a straight line, and I think that is worth saying plainly rather than smoothing over. Mechatronics to software, Karachi to Manchester, client work to product. What carried across was the engineering habit of not trusting a system until you have measured it.

Technical

TypeScript React Next.js React Native Node.js / Express GraphQL LLM streaming & tool calling AWS Bedrock AI agents Vercel AI SDK AWS (VPC, API Gateway, Lambda) Terraform PostgreSQL MongoDB Docker Vite / Rollup CI/CD AST & parser internals

Get In Touch

I am glad to hear from maintainers, reviewers and engineers working on the same problems: build tooling, parser internals, or getting AI to behave predictably inside real product surfaces.