Fit the product
Stack decisions follow your constraints — team, timeline, compliance, scale — not what's popular this quarter.
Engineering stack
Technologies we use to ship products that last
Zestlan engineers across AI, web, mobile, cloud, DevOps, data, and security — selecting tools for production reliability, auditability, and maintainability. Not novelty. Not lock-in for its own sake.
Selection principles
We pick tools for your product — not our résumé.
The right stack is the one that lets your team ship safely, operate confidently, and change direction without a rewrite.
Production is the bar
If it can't handle real traffic, real failures, and real operating cost, it doesn't ship.
Secure from commit one
Threat modeling, identity, and secrets management are part of setup — not a pre-launch panic.
Maintainable for years
We optimize for the team that owns the product after us — clear boundaries, docs, and boring technology where boring wins.
Stack by layer
Full-stack depth across every product layer
AI, application code, mobile clients, data, cloud infrastructure, and security — the layers we engineer every week on client programs.
From prototype to monitored production
AI & Machine Learning
LLM applications, RAG, agents, and classical ML — with evaluation harnesses, guardrails, and observability so AI features behave predictably under real usage.
OpenAI & GPT APIsLangChain / LlamaIndexHugging FaceTensorFlowPyTorchRAG pipelinesVector databases (Pinecone, pgvector)Model evaluation & guardrails
Right tool for the workload
Languages
Polyglot engineering across typed frontends, high-throughput backends, data processing, and mobile — matched to performance, team, and maintenance requirements.
TypeScriptJavaScriptPythonJavaGoPHPSwiftKotlin
Products users feel — APIs teams trust
Web & API Platforms
Modern web frameworks and API layers chosen for developer velocity, security, and long-term ownership — not framework fashion.
ReactNext.jsVueAngularNode.jsNestJSLaravelDjango.NETGraphQLREST APIs
Store-ready, enterprise-connected
Mobile Engineering
Native and cross-platform mobile stacks with release pipelines, push, deep links, and offline patterns for workforce and customer products.
Swift (iOS)Kotlin (Android)FlutterReact NativeApp Store / Play release engineeringPush notifications & deep links
Integrity, speed, and search — matched to access patterns
Databases & Data Platforms
Relational cores, document stores, caches, and search indices — with migration discipline, backups, and pipelines that keep reporting honest.
PostgreSQLMySQLMongoDBRedisElasticsearchDynamoDBFirebaseData pipelines & ETL
Ship often. Sleep at night.
Cloud & DevOps
Multi-cloud infrastructure, containers, IaC, and CI/CD pipelines that make releases routine and incidents diagnosable.
AWSAzureGoogle CloudDockerKubernetesTerraformCI/CD (GitHub Actions, Jenkins)Monitoring & observability
Live data without live incidents
Realtime & Event Systems
Messaging, streaming, and realtime protocols for products where latency and reliability both matter — collaboration, logistics, and operations platforms.
WebRTCSocket.IOKafkagRPCPub/Sub messagingLive video / SFU architecturesEvent-driven microservices
Defensible by design
Security Engineering
Identity, encryption, API security, and audit infrastructure for products that face internal security review or external regulation.
OAuth 2.0 / OpenID ConnectJWT & SSOAPI security hardeningEncryption at rest & in transitPenetration testing readinessAudit logs & access controlSecure SDLC practices
How we ship
Stack means nothing without delivery discipline
Tests, pipelines, observability, and documentation — the engineering habits that keep products healthy after the launch announcement.
- Modular architecture that supports product growth without rewrites
- Versioned APIs and explicit service contracts
- Automated test, build, and deploy on every meaningful change
- Metrics, logs, and traces for performance and incident response
- Runbooks and knowledge transfer for your internal team
- Post-launch tuning for cost, speed, and reliability
Unsure which stack fits your product?
Walk us through your product, scale targets, and constraints. Our architects will recommend an approach — and stay to build it if you want one team end to end.