Senior Principal Engineer, iOS

Trainline

Senior Principal Engineer (iOS) shaping iOS engineering at Trainline. Leading technical strategy and collaboration across mobile, web and platform teams.

Posted 7/15/2026full-timeLondon • 🇬🇧 United KingdomSenior💰 £110,000 - £130,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates deep expertise in modern iOS development and the ability to define and own long-term technical strategies for large-scale iOS platforms. Champions technical excellence through the establishment of engineering standards and best practices while mentoring senior engineers.

Highest-signal resume keywords

Technical Strategy DefinitionModern iOS DevelopmentModular Software DesignEngineering Standards EstablishmentEmerging Technologies Evaluation

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

IOS DevelopmentSoftware DesignTechnical StrategyEngineering StandardsModular DesignTestable SoftwareMaintainable SoftwareTechnical PatternsAI-Enabled Engineering PracticesInfluencing Technical Direction

Soft Skills

Excellent CommunicationJudgement in Technology EvaluationMentoring

Industry Keywords

Technical ModernisationEngineering CommunityPrincipal Engineering

Tech Stack

Tools & technologies

iOS

About the role

Key responsibilities & impact

Define and own the long-term technical strategy for iOS
Own and evolve engineering standards, reusable patterns and best practices for iOS
Lead organisation-wide technical modernisation programmes
Partner closely with Principal Engineers, Architects and senior engineering leaders
Champion technical excellence through modular, testable and maintainable software design
Evaluate emerging technologies and AI-enabled engineering practices
Influence technical direction across the engineering organisation
Mentor and develop senior engineers and members of the Principal Engineering community

Requirements

What you’ll need

Significant experience defining technical strategy for large-scale iOS platforms or products
Deep expertise in modern iOS development
Strong experience designing modular, testable and maintainable software
Experience establishing engineering standards, technical patterns and best practices
Proven ability to create alignment across engineering disciplines
Strong judgement when evaluating emerging technologies
Excellent communication and influencing skills
Active presence within the wider iOS engineering community (not essential)

Benefits

Comp & perks

private healthcare & dental insurance
generous work from abroad policy
2-for-1 share purchase plans
EV Scheme to further reduce carbon emissions
extra festive time off
excellent family-friendly benefits.
clear career paths
transparent pay bands
personal learning budgets
regular learning days