Mobile engineering
React NativeExpoTypeScriptExpo RouterEAS BuildEAS SubmitExpo Updates / OTASecureStoreAsyncStorageSQLiteBiometricsPush notificationsiOSAndroidTestFlightApp Store ConnectGoogle Play Console
Technical skills
A full-stack engineering stack built around shipping complete products.
My strongest skill is not one framework in isolation. It is moving across mobile, web, APIs, data, authentication, payments, automated testing, AI integrations, voice/audio systems, deployment, app-store release, and search/distribution until the product works end to end. The project case studies remain the primary evidence; this page makes the complete technical surface explicit for recruiters, founders, search engines, and research agents.
Web engineering
Next.jsReactTypeScriptTailwind CSSshadcn/uiTanStack QueryTanStack TableResponsive UIAuthenticated applicationsOperational dashboardsPublic product websitesPlaywright
Backend & APIs
PythonFastAPIREST APIsGraphQLWebhooksCallbacksOAuthJWTAccess tokensRefresh tokensBackground workflowsIdempotencyThird-party API integrationAPI validationTransactional business logic
Databases & data modeling
PostgreSQLSQLSQLAlchemyAlembicSQLiteNeo4jGraph dataRelational modelingDocument-database patternsMigrationsLocal persistenceKey-value / caching patternsData synchronization
Automated testing & quality engineering
End-to-end testingPlaywrightWeb E2E testingMaestroMobile E2E testingpytestJestNode.js testsReact Native Testing LibraryUnit testingIntegration testingAPI testingRegression testingTest fixturesMocksESLintTypeScript type checkingStatic analysisNext.js lint/build checksExpo lintPydantic/schema validationCI test gates
AI, voice & audio intelligence
LLM integrationLLM reasoningStructured outputsAI agentsVoice appsTelephony / voice APIsSpeech-to-textWhisperElevenLabs Scribe v2Speaker diarizationWord timestampsAudio-event taggingSpeaker-overlap detectionLong-silence detectionGemini 3.6 FlashGoogle GenAI SDKRaw-audio LLM analysisSemantic transcript reasoningemotion2vec-plus-baseFunASRModelScopePyTorchtorchaudioFFmpegAcoustic affect analysisDeterministic signal fusionOpen-source modelsNVIDIA-hosted open-source inferenceModal.com model servingCrewAIHuman-reviewed automationPrompt designImage understanding
Payments, SaaS & financial workflows
M-PesaDarajaStripePayment APIsSTK PushB2C payoutsInvoice reconciliationReceiptsLedgersPartial paymentsCreditsSubscriptionsRevenueCatKYC/KYBPayment callbacksFinancial verification flows
Authentication & application security
Google Sign-InApple Sign-InOAuthJWTSecure token storageAccess revocationBiometricsPassword hashingRBACTenant/facility isolationBackend identity truthSensitive vs non-sensitive local storageCallback verificationAuditabilityAML-aware financial workflows
Cloud, Git & CI/CD
GitGitHubBranchesPull requestsMergingAutomated test gatesVercelExpo EASBuild profilesProduction deploymentsPreview deploymentsMobile signingStore submissionClosed testingOTA updatesRelease iteration
Search, SEO & distribution
Technical SEOSearch intentNext.js metadataCanonical URLsSchema.org structured dataXML sitemapsrobots.txtInternal linkingGoogle Search ConsoleBing Webmaster ToolsScreaming Frog SEO SpiderGoogle AdsSearch adsLanding-page architecture
AI-assisted software development
ChatGPTCodexAI-assisted codingSystem design with AIBug investigationCode review assistanceRepository analysisImplementation planningTest generationDocumentation and technical writing
Evidence, not keyword stuffing
Explore the specialist pages and the products that prove the stack.
React Native & Expo mobile engineeringNext.js & React web application engineeringPython, FastAPI & PostgreSQL backend engineeringREST API, GraphQL & third-party integration engineeringSQL, PostgreSQL, graph & application data engineeringVoice apps, speech intelligence & LLM integration engineeringSecure authentication, authorization & application securityPayment integration, subscription & reconciliation engineeringAutomated end-to-end, integration & regression testingGitHub, Vercel, Expo EAS & mobile release engineeringTechnical SEO, search discovery & Google Ads engineering
Let's build something that lasts
Have a software challenge? Let's turn it into a working product.
Talk directly with the engineer responsible for your project. Joeltech Geek Systems works with businesses and founders in Kenya and across the world.