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WeAreDevelopers LIVE • Oct 6, 2023

Migrating half a million users to a new payment service provider

Sebastian Hans

Faced with a strict 3.5-month deadline, engineers bypassed risky big-bang releases for fine-grained code routing. Discover how they safely migrated half a million payment users using Kotlin.

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#1 about 3 min

Introduction to software development as a sociotechnical system

Software development fundamentally functions as a sociotechnical endeavor where team dynamics and stakeholders dictate success as much as the code itself.

#2 about 7 min

Interactive audience exercise exploring devops and production operations

An interactive workshop exercise captures attendee backgrounds and explores their foundational principles for performing major technical operations in production.

#3 about 4 min

Technical architecture overview and payment integration project constraints

The login ecosystem architecture mandates a tight timeframe for executing a live payment provider migration without system downtime.

#4 about 4 min

Navigating challenges in testing payment service provider APIs

Reverse engineering poorly documented endpoints and dealing with manual vendor configurations severely restrict exhaustive testing capabilities before production.

#5 about 3 min

Project planning strategies against hard implementation deadlines

Backwards and forwards schedule planning aligns legal user notification mandates with an extremely narrow consolidation testing phase.

#6 about 5 min

Technical logic behind SEPA direct debit processing flows

The mechanics of payment processing require securing SEPA mandates upfront, authorizing the transaction risk, and initiating delayed batch captures.

#7 about 8 min

Interactive polling exercise evaluating technical migration strategies

A collaborative analysis weighs the risks of routing updates by individual users against bulk migrating distinct software services.

#8 about 7 min

Building custom routing logic per user for controlled rollouts

Anchoring user-level routing logic in the application code safely bypasses monthly billing cycle complications while preventing runaway vendor costs.

#9 about 8 min

Discussing unexpected feature requests along the critical path

An interactive evaluation explores how to accommodate a rapid frontend feature for upfront mandate grants despite ongoing core migration tasks.

#10 about 3 min

Delivering iterative visual feedback loops for user interfaces

Deploying minimal frontend capabilities and subsequently refining them with rapid visual cues effectively drops customer support escalations.

#11 about 8 min

Interactive problem solving for delayed vendor legal contracts

Brainstorming evaluates emergency pathways and fallback techniques for handling partner services that lack finalized legal contracts before the scheduled go-live.

#12 about 6 min

Deploying fallback code and managing go-live vendor errors

Embedding a legacy vendor fallback directly into the codebase isolates un-contracted services and mitigates manual configuration bugs occurring on the provider side.

#13 about 8 min

Interactive troubleshooting for unexpected network timeout errors

Collaborative debugging explores how increasing network timeouts risks degrading the checkout experience versus pausing migration batches altogether.

#14 about 4 min

Resolving payment timeouts through direct partner risk negotiation

Securing an agreement with the new vendor to temporarily absorb default risk bypasses frontend timeouts and stabilizes the checkout process.

#15 about 7 min

Post-migration technical debt cleanup and sociotechnical reflections

Removing obsolete routing code leaves a clean architecture while cementing crucial principles around business context, fast feedback loops, and operational agility.

#16 about 11 min

Company culture, career paths, and technical talent acquisition

Human resources leaders highlight the organization's employee-oriented focus, internal development trajectories, and wide-reaching technical impact on municipal infrastructure.

#17 about 5 min

Evaluating technical routing choices and industry discovery tactics

Answers to technical inquiries explore how the initial cohort of friendly test users was gathered and whether external corporate benchmarks were audited.

#18 about 9 min

Discussing backend technical stacks and balanced performance evaluations

Explanations outline a modern backend environment reliant on Kotlin and avoiding flawed arbitrary metrics in favor of holistic peer feedback evaluations.

#19 about 7 min

Codebase archival practices and app store customer feedback

Technical principles dictate fully pruning deprecated provider code rather than archiving it, while analytics indicate minimal disruptions to end-user platform ratings.

#20 about 11 min

Analyzing candidate soft skills and developer onboarding frameworks

Recruiters emphasize finding cohesive, communicative peers, highlight extensive German language support, and detail the technical ramp-up cycle for inbound developers.

Matching moments

1:04 min

Recognizing the social realities of technical migrations

Robert Lehmann Robert Lehmann · World Congress 2026 Europe

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Executing massive cloud network migrations while maintaining live systems

Dana Lawson Dana Lawson +1 · World Congress 2026 Europe

4:36 min

Hiring passionate software engineers to tackle unprecedented scaling challenges

Dana Lawson Dana Lawson +1 · World Congress 2026 Europe

5:00 min

Evolving engineering culture across global product teams

David Singleton David Singleton +1 · World Congress 2023

1:15 min

Accelerating application migration strategies with flexible routing

Duan Lightfoot Duan Lightfoot · World Congress 2023

1:06 min

Securing enterprise funding to refactor unscalable procedural shortcuts

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