Custom Software Development Agency
We build software that fits your business, not the other way around. For 20 years, Coalesce has helped companies ship products that off-the-shelf tools can't handle.
Since 2006
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$125M+ client revenue supported
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4+ year avg. client relationship
Whether you're building from scratch or extending what you have, we bring senior engineers and strategic thinking to every engagement. We turn competitive advantages into custom platforms, connect systems that don't talk to each other, and ship products that actually fit how your business works.
When off-the-shelf stops working
You've probably tried the obvious solutions. Salesforce plugins, Zapier workflows, that SaaS tool your competitor swears by. At some point, duct tape and workarounds stop scaling. You need something built around how your business actually works.
Your workflow is the product.
The thing that makes your business different can't be bought off the shelf. Whether it's how you onboard customers, process transactions, or connect data across systems, your competitive advantage needs custom software behind it.
You've outgrown the tools you started with.
What worked at 10 employees or 1,000 users is now a bottleneck. Your CRM doesn't know what your billing system knows, your ops team is copy-pasting between dashboards, and nothing scales the way the business needs it to. You need systems that talk to each other — and software built around how your business actually works.
Sometimes the problem isn't the product — it's the team that built it.
If a previous agency left you with an incomplete build, a codebase nobody wants to touch, or a product that worked in the demo and fell apart in production, that's a situation we know well. We've spent 20 years inheriting those projects and making them right. We don't need to start from scratch to make meaningful progress — and we won't tell you that you do.
Technologies we work with
For brownfield work, we meet your existing stack where it is — no unnecessary migrations. For greenfield builds, we're deliberate: AI-augmented development performs best on well-supported modern stacks, and we design new projects with that in mind.
Frontend
React, Next.js, Vue.js, TypeScript, GSAP, Astro, Tailwind CSS, SCSS / Sass
Backend
Node.js, Laravel, Python, Spring Boot, PHP
Databases
PostgreSQL, MySQL, MongoDB, Redis
DevOps & Infrastructure
AWS, Cloudflare, Docker, Kubernetes, GitHub Actions, Firebase, Vercel
Mobile
iOS (Swift), Android (Kotlin), React Native
AI & Machine Learning
OpenAI API, Anthropic Claude API, LangChain, RAG architectures, vector databases (Pinecone, pgvector), embedding pipelines
Services
Legacy Modernization
Upgrade aging systems without rebuilding from scratch
API Development & Integrations
Connect your tools and automate manual workflows
AI Implementation
Add intelligence layers to existing products
Custom Web Applications
Platforms built around your unique business logic
Mobile Development
iOS and Android apps that scale with your users
Ongoing Support & Maintenance
Security, performance, and continuous iteration
Process
1. Discovery
We start by understanding your business: goals, constraints, existing systems (if any), and what success looks like. No 200-page audits.
2. Strategy
A prioritized roadmap based on your constraints. What's urgent vs. important. What we can ship in weeks vs. what needs architectural work. Clear trade-offs, not hand-wavy estimates.
3. Build
AI-augmented development with human review at every decision point. Whether we're starting fresh or working in your existing stack, you get senior engineers. No handoffs.
4. Launch
QA, deployment, and monitoring. We don't ship and disappear.
5. Iterate
Ongoing partnership, not a handoff. We stick around to make it better.
A note on security
We treat security as a foundational requirement, not a checklist item. That means OWASP-informed code reviews, secrets management, dependency auditing, and proper auth patterns from the start — not a security pass at the end of the sprint.
Recent Case Studies
Coalesce brought a rigorous development approach, meticulous attention to detail, and creative suggestions to the process. The team was clearly invested in the project's success and has become a trusted, valuable collaborator.
Morgan Brown
Inman News
FAQ
What industries do you work with?
We've built custom software for Education, Financial Services, Online Publishing, Real Estate, Health Care, Non-Profit, Hospitality, Manufacturing, Entertainment, Internet, Fashion, and Consumer Goods-among others.
How long does a typical project take?
It depends on scope. A focused MVP or integration project might take 6-10 weeks. Larger platform builds typically run 4-8 months. We'll give you a realistic timeline after discovery.
Do you work with existing codebases?
Yes-it's our specialty. We call it brownfield development. We assess what you have, identify what's worth keeping, and build from there.
Where is your team located?
We're headquartered in New York City, with senior engineers across the Americas and Europe. Our distributed team means faster turnaround without sacrificing quality or communication.
How do you price projects?
Most engagements start with a focused discovery phase, then move into monthly retainers for ongoing development and support. We scope work as fixed-fee or monthly retainers depending on the nature of the project. Full builds vary based on complexity. We're not optimizing for one-off projects. We partner with teams who want a long-term engineering relationship.
How do you handle a codebase you didn't write?
Carefully, and with respect for the decisions that got it here. We've developed a systematic approach to codebase onboarding: reading code to understand intent, tracing behavior through the system, mapping dependencies, and identifying patterns before touching anything. We typically reach meaningful productivity within 2–4 weeks on a new codebase. Our default is to improve incrementally — not rewrite — unless the architecture is fundamentally misaligned with where the product needs to go.
What does "AI-augmented development" actually mean in practice?
It means our engineers use AI tools to accelerate the parts of development that benefit from acceleration — generating boilerplate, drafting tests, writing documentation, and doing initial code review passes. Every output goes through human review before it becomes part of your codebase. Our senior engineers make the architectural decisions, handle the judgment calls, and own the quality of what ships. AI handles the first draft; humans handle everything that actually matters.
What's the difference between a fixed-fee and retainer engagement?
Fixed-fee works well when the scope is well-defined — a discrete build, integration, or feature set where we can draw clear boundaries around what's included. Retainers work better for ongoing development, brownfield work, or situations where requirements are likely to evolve. Most of our longer-term client relationships start with a fixed-fee discovery or initial build, then move into a retainer as the partnership deepens. We'll tell you which structure makes sense for your situation.
What happens if requirements change mid-project?
They always do. We build change into how we work rather than pretending a spec written at the start of a project will survive contact with reality. On fixed-fee projects, material scope changes get discussed openly and repriced if needed — no surprises. On retainers, we adjust priorities collaboratively as your needs shift. The goal is a partnership where you can tell us what changed without worrying about a change order fight.
Ready to build something that lasts?
We support $125M+ of client revenue annually with a lean team of senior engineers. Let's talk about what you're building.