About the author

Raúl Hernández López | Raul Hernandez Lopez

AI Software Engineer | Senior Staff Software Engineer in Mobile Teacher

NLP & Pattern Recognition | Ex-Twitter & Zendesk | Remote | Available Sep 2026 (flexible)

Public Speaking, Technical Writing, Open-source Projects, Tech Blog

Bridging the gap between Scalable Platforms and Artificial Intelligence.

Who am I? After 12+ years architecting high-performance mobile apps and complex systems for global leaders like Twitter and Zendesk, I am pivoting to the intersection of Software Engineering and AI. Entering the final phase of an M.Sc. in Artificial Intelligence (MIARFID) at UPV with all core coursework completed, and currently focusing on my final thesis, specialising in NLP, Computer Vision, and Deep Learning.

Engineering DNA: Across my career, I’ve led critical projects and helped shape healthy engineering cultures through communities of practice (part of my DNA as a Staff+ engineer). Depending on the needs of my team, I’ve worn many hats: from tech lead to team lead, balancing delivery with mentoring and long-term architecture thinking.

Technical Context:

  • Engineering: Kotlin, Android, System Design, Scalable Architecture.
  • AI (Current Focus): Python, Machine Learning, NLP, Computer Vision, Data Visualisation, Biometrics.

Contents

Applied AI projects

Research and engineering work carried out during the M.Sc. in Artificial Intelligence (MIARFID) at UPV, most recent first.

EXIST 2026 competition (CLEF) — Academic research in NLP

February 2026 – July 2026 · Lead AI Engineer · Team NeverChorizoInMyPaella (Giuseppe Di Palma & Raúl Hernández López)

Part of the ALC (Applications of Computational Linguistics) module, where I achieved a Distinction (MH).

  • AI architecture & implementation: led the engineering of a cascade NLP model in Python and PyTorch, progressing from raw data ingestion to sexism identification, categorisation and intention, designed for classifying sexist content in social media (TikTok) videos.
  • Technical achievement (1st place): secured the 1st global position in the Categorisation (soft-soft context) evaluation by applying the LeWiDi (Learning with Disagreement) paradigm to handle highly nuanced and ambiguous language coming from different annotators and their psysiological data (HR, EEG and ET).
  • Testing & QA validation: ran rigorous functional validation and evaluation of AI outputs with PyEvALL, identifying model inconsistencies across diverse datasets to improve reliability against the official competition metrics (F1 for majority voting, ICM for soft evaluation).
  • Research & publication: co-authored an accepted academic paper detailing the model architecture, methodology and evaluation, presented at CLEF 2026 (21–24 September 2026).

Links: EXIST 2026 ranking and info · CLEF 2026 Working Notes

Paper reference: “NeverChorizoInMyPaella at EXIST 2026: Multimodal Sexism Identification and Categorisation in TikTok Videos via Sequential Cascade Training and Visual Cross-Attention”, pp. 2202–2215 — Giuseppe Di-Palma, Raúl Hernández-López.

Early sepsis detection and trade-off in models — Academic research on tabular data

February 2026 – May 2026 · Group project

Part of the ARA (Pattern recognition and machine learning applications) module, graded 9.6 out of 10.

  • Data curation & feature engineering: investigated and curated data from a cardiology challenge dataset, using tree-based models to engineer features, optimise hyperparameters and select an appropriate decision threshold via a cascade approach, with stratified cross-validation in 3 folds.
  • Explainability: added an explainability layer on top of the pre-trained XGBoost model to understand which variables drive the early prediction of sepsis.
  • Metric selection: chose metrics adjusted to clinically relevant trade-offs, such as AUPRC.

Link: Presentation

Georeferenced running data visualisation — Data science

February 2026 – June 2026 · Individual project

Part of the Data Visualisation module.

  • System integration & API: integrated Python data-processing components with external API endpoints, handling structured mapping data inside a Streamlit application.
  • Data security: implemented strict data encryption to protect personal user information, keeping robust privacy standards for sensitive health and fitness data.
  • Algorithmic optimisation: engineered Python utilities to programmatically process complex datasets with robust data handling. Link: Web app | GitHub repository

Local RAG assistant — Agents and RAG research in NLP

November 2025 – January 2026 · Individual project

Part of the Human Language Technologies course.

  • RAG architecture & document ingestion: architected and implemented a local Retrieval-Augmented Generation pipeline in Python, handling document ingestion and chunking strategies for unstructured data.
  • Embeddings & search: integrated a vector database (Qdrant) for efficient similarity search and embedding storage.
  • AI agent orchestration: orchestrated local LLMs (Ollama) with LangChain to build an automated conversational workflow inside a Streamlit application.

Link: GitHub repository

Half-marathon plan generator — Algorithmic research

September 2025 – November 2025 · Individual project

Part of the Metaheuristic Techniques module.

  • Algorithmic optimisation: engineered a scalable Python utility to generate and optimise training plans from baseline performance metrics.
  • Open-source architecture: built the solution with clean, maintainable Python principles, strict version control, and released it as a FOSS repository.

Link: GitHub repository

Work experience

Industry roles, most recent first.

Formerly

  • Remote Senior Staff Software Engineer (Mobile and SDKs) at Zendesk from March 2024 until June 2025.
    • Created delightful Customer Experiences (CX) with the best teams at Zendesk.
    • Group Tech Lead for Mobile SDKs: Android, Unity and iOS & Mobile Apps (Support): Android and iOS.
    • Worked on the Android Native Messaging SDK.
    • Worked on Scaling Mobile SDKs and Apps.
    • Architect, Group Tech Lead and Mentor.
  • Remote Staff Software Engineer (Mobile SDKs) at Zendesk from June 2022 until February 2024.
    • Helped Zendesk creating delightful customer experiences for the Mobile SDKs team.
    • Mobile SDKs.
    • Worked on the Android Native Messaging SDK.
    • Worked on Scaling Mobile SDKs.
    • Architect, Tech Lead and Mentor.
  • Remote Senior Software Engineer - Android at Twitter in EMEA timezone from July 2018 until April 2022
    • Fully Remote from 2020 to 2022.
    • Founding Engineering member for the Twitter Blue team. Jan’21 - April’22. Introducing Twitter Blue - Twitter’s first-ever subscription offering
    • Collaborated for the Consumer Search Clients (CSC) team. Dec’19 - Jan’21
    • Collaborated for the Live Events / Events Clients (EC) team. Apr’18 - Sep’18 & May’19 - Dec’19.
    • Collaborated for the Periscope / Go Live Together (Hydra) team. Oct’18 - Apr’19
    • Roles:
      • Software Engineer.
      • Project Tech Lead (PTL).
        • Mentor for members of my teams.
        • Kotlin Shepherd, for our Kotlin community active member (Kotlin & QE Automation shepherd).
        • Luna Shepherd, helping interview huddles to embrace good practices).
    • Tech debt & architectural optimisations (PTL / Tech design shepherd).
    • Engineer on call to fix issues (maintainer).
    • Speaker & Driver/Enabler for Internal/External tech events / talks / podcasts.
    • Active interviewer for hiring new candidates for:
      • All levels: SWE 1 to Sr SWE.
      • All surfaces / platforms: Android -> specific expertise interview or iOS & RWEB -> general technical interviews.
  • Senior Software Engineer - Android (contract) at Twitter in London (UK) - from April the 30th to July 2018.
    • Collaborating for Live Events team.
  • Lead Android Developer / Chapter Android Lead at Touch Surgery in London (UK) June 2017 until April the 27th 2018
  • …more at the bottom section…

2023 Public speaking

  • Panel: “What I wish I knew when I was a junior developer that I would tell as a staff software engineer” at Droidcon Berlin (Germany) (July).

2022 In general

2021 Public speaking

2021 Public written technical articles

2020 Public speaking

  • “Fueled Reactive apps with Asynchronous Flow & StateFlow to Sync with the UI” at Droidcon APAC (Dec).
  • “Fueled Reactive apps with Asynchronous Flow & StateFlow to Sync with the UI” at Kotlin London User Group (KUG) meetup (Dec).
  • “Fueled Reactive apps with Asynchronous Flow & StateFlow to Sync with the UI” at Kotlin Munich User Group (KUG) meetup (Nov).
  • “Fueled Reactive apps with Asynchronous Flow & StateFlow to Sync with the UI” at Madrid Android Developer Group (MADG) meetup (Nov).
  • “Fueled Reactive apps with Asynchronous Flow (& StateFlow to Sync with the UI)” at Droidcon EMEA (Oct).
    • Featured at Kotlin #221 Weekly
    • v2 explains in detail a full migration from RxJava 2 to Kotlin Coroutines & Flows / StateFlow / Channels.
    • Video
    • Slides
    • v2 Basics section was reduced going to the key points only in order to include a new section migrating Clean Architecture Callbacks on behalf of Kotlin StateFlow for Synchronous communication with the UI.
  • “Fueled Reactive apps with Asynchronous Flow” interview at AndroidDevPodcast with David Hackro (Jul)
    • Podcast audio interview (in Spanish)
    • We discussed step by step, talking about keypoints and reasoning behind why we would like to migrate a well-assembled Android app with a pre-existing foundation using RxJava 2 to use Kotlin Flow and friends instead.
  • “Fueled Reactive apps with Asynchronous Flow” v1 at Android Makers (Paris, France) - Virtual Android Makers edition (Apr).
    • v1 explains in detail a full migration from RxJava 2 to Kotlin Coroutines & Flows / Channels.
    • Video
    • Slides
    • v1 includes a longer Basics section as well as Asynchronous communication section. Migration for Clean Architecture and View Delegates to Kotlin Flow & Channels with Coroutines. Callbacks still pass results from the Use Cases / Interactors.
  • “Qué necesita un desarrollador para alcanzar sus metas?” interview at DevExperto’s “I stay at home” series with Antonio Leiva (Mar).

2020 Public written technical articles

2019 Public speaking

  • “Pushing Dynamic Features Your Users Want, As Quick As They Want Them”.

2018 Public written technical article

2017 Public speaking

  • “Building a Minimum Viable Product (MVP) with Face recognition and AR” at Droidcon UK (London) in October.
  • Light talk “Quest of a Hero” at Londroid April.
  • Light talk “From junior to experienced in few years” at Freakend Mobile in February.

Public code snippets & side projects

Studies

  • MSc in Artificial Intelligence, Pattern Recognition, and Digital Imaging specialisation in Human Language Technologies and Pattern Recognition at Polytechnic University of Valencia (UPV), (Valencia, Spain)
    • September 2025 onwards
  • MEd in Compulsory Secondary and Upper Secondary Education, Vocational Training and Language Teaching specialisation in Technology and Computer Science at Universidad Internacional de La Rioja (UNIR), (Spain, online)
    • February 2025 to February 2026
  • MSc Computational & Software Techniques in Engineering specialisation of Software Engineering at Cranfield University (Cranfield, UK)
  • Engineer in Computer Science specialisation in Software Engineering (second cycle) & Information Systems (first cycle) or BSc(Hons) Information Systems + MSc Software Engineering (BSc + MSc is equivalent to the Spanish Engineer degree) at Polytechnic University of Valencia (UPV), (Valencia, Spain)
  • BSc(Hons) Information technology at Edinburgh Napier University (Edinburgh, UK)

Hobbies

I do enjoy meeting new cultures, learning from others & self-learning myself, listening rock / metal music, running, reading or travelling.

Extension of Formerly work experience

  • Senior Android Developer at Supe app / Rise Project UK London (UK) 2016-2017
  • Android developer at YouView in London (UK) 2015-2016
  • Senior Android Developer working at a startup called Critizen app / Next Chance Stocks SL in Madrid (Spain) 2015
  • Android Developer and Team Lead (contract) at a mobile little agency called Mobilendo in Valencia (Spain) 2014-2015
  • Software Development Engineer - C++ (contract) at the Mid-back office for Amadeus (on behalf of Harvey Nash) in Antwerp (Belgium) 2013-2014
  • Junior Software developer at Openbet in London (UK) 2012-2013
  • Junior Researcher and Android Software Engineer at Cranfield University (Erasmus internship) in Cranfield (UK) 2012
  • Technical Engineer In Administrative Data Processing at Common Council of Valencia (contract / internship granted for <30 recently graduates) in Valencia (Spain) 2010-2011
  • Junior Software engineer - PHP at a “bioinformatics startup” called Biotechvana in Valencia (Spain) 2010
  • IT Support and Development staff (contract) at Servipoli - Polytecnic University of Valencia (uni students job granted) in Valencia (Spain) 2008-2009
  • IT Support Staff at Valencian Institute of Statistics and applied sciencies (internship granted) in Valencia (Spain) 2007-2008

Social media

Other public profiles