Should Your Next App Be Monolithic or Microservices?

One of the never-ending debates in the tech industry is which software architecture is better: monolithic or microservices? 

Each organization has their preference, but most will agree that a monolith is a better starting point for a new product, whereas microservices can come very much in handy as your user base and complexity grows. 

Key takeaways: 

• Start simple - most applications begin as monoliths unless you have specific, compelling reasons for complexity.

• Follow team growth - architecture should match your organizational structure and capabilities.

• Plan for evolution - design your monolith with clear business domain boundaries for future service extraction. Organize code around business capabilities, not technical layers.

• Measure business impact - track metrics like deployment frequency, lead time, and customer value delivery.

• Budget for operations - microservices require significant investment in tooling, monitoring, and expertise. Factor in the operational complexity and infrastructure costs before making the leap.

What's the Real Difference Between Monolithic and Microservices Architecture?

Think of it this way: a monolithic application is built as a single unit, where all your logic for handling requests runs in a single process. 

It's like a single building where every department (accounting, customer service, inventory, marketing, etc.) operates under one roof, sharing the same infrastructure, power systems, and foundation. 

Meanwhile, microservices architecture is an approach to developing a single application as a suite of small services, each running in its own process and communicating with lightweight mechanisms.

So it’s more like a business campus where each department has its own specialized building, complete with independent power, security, and operations. Or a company that outsources business functions to various third-party companies around the world. 

Monoliths Make Things Simpler In The Beginning

Let’s use another analogy - restaurant kitchens. 

In a monolithic setup, you have one massive kitchen where a single team handles everything. Prep work, grilling, pastry, salads, and plating are all done in the same space with shared equipment and storage.

This approach makes coordination easier initially. But as the restaurant grows busier, bottlenecks emerge. If the grill breaks down, it affects the entire operation. If you need to hire more pastry chefs, they compete for space with the salad team.

In contrast, microservices architecture resembles a restaurant with specialized stations: a dedicated prep kitchen, separate grill station, pastry department, salad bar, and plating area. 

Each station operates independently with its own equipment, staff, and workflows. Each microservice is built around business capabilities, just like how each kitchen station focuses on specific culinary functions. The pastry station can upgrade its ovens without affecting the grill. If the salad station goes down for maintenance, the rest of the restaurant continues operating.

What Are Key Characteristics Of Monolithic And Microservices Architectures?

The monolithic architecture is characterized by a single codebase, a shared database, all-or-nothing deployment, and uniform technology.

• Single codebase - all components are tightly coupled and run in the same process

• Shared database - everyone accesses the same data storage system

• All-or-nothing deployment - any changes require rebuilding and deploying the entire application

• Uniform technology - the whole application typically uses the same technology stack

The microservices architecture is defined by independent services, decentralized data, API communication, and technology diversity.

• Independent services - each service is independently deployable and replaceable

• Decentralized data - each service manages its own database

• API communication - services talk to each other through well-defined interfaces

• Technology diversity - different services can use different programming languages and frameworks

How Monolith vs Microservices Choice Affects Day-to-Day Operations

The architectural choice fundamentally changes how your development teams work.

In monolithic systems, teams are often organized around technical layers. You might have separate UI, business logic, and database teams. Simple changes often require coordination across multiple teams. Research from IEEE shows this can slow development cycles, especially as the codebase grows larger.

With microservices, teams are organized around business capabilities. Each team owns their service from front to back, including its user interface, business logic, and data storage. Netflix, which successfully transitioned from monolithic to microservices, now deploys code changes multiple times daily because teams can work independently without stepping on each other's toes.

Monolithic applications must be scaled as a whole, even if only one feature needs more resources. If your user authentication system is overwhelmed, you need to add more servers for the entire application, even though your reporting features are running fine.

Microservices allow independent scaling of individual services. During peak shopping hours, you can scale up your payment processing service while leaving your user profile service unchanged. Companies take advantage of this to handle issues like varying demand across different geographic regions and services.

Any change to a monolithic application requires redeploying the entire system, creating an all-or-nothing risk scenario. It's like shutting down an entire shopping mall to renovate one store. Some studies indicate this often leads to longer, riskier deployment cycles and resistance to frequent updates.

Microservices enable independent deployment of individual services, reducing deployment risk and allowing faster iteration. If a bug appears in your recommendation engine, you can fix and deploy just that service without touching your payment system. However, this comes with increased operational complexity. You now have multiple services to monitor, deploy, and maintain.

Monolithic applications offer simpler debugging experiences since all code runs in the same process. When something breaks, you have one log file to check and one system to debug.

With microservices, debugging becomes more complex as issues might span multiple services. You need sophisticated monitoring tools to trace requests across services. This requires additional investment in observability tools and practices.

Monolithic systems often separate development and operations teams, which can lead to the classic "it works on my machine" problems but may be simpler for organizations without mature DevOps practices.

Microservices encourage the "you build it, you run it" philosophy, where teams take full responsibility for their services in production. This creates stronger ownership but requires teams to develop broader skill sets, including operations and monitoring capabilities.

Why Do Startups Usually Choose Monolithic Architecture?

Monolithic architecture gets products to market faster and cheaper for early-stage companies, with lower technical complexity and fewer moving parts to manage.

For most startups, architectural sophistication matters less than pure survival. When you're racing to validate a business idea and reach customers before running out of funding, monolithic architecture offers rapid development, elegant code structure, and the ability to ship features quickly. It's a strategic advantage that lets small teams focus on building products instead of managing infrastructure complexity.

Monoliths Foster Speed to Market

Time is the most precious resource for any startup, and monolithic architecture delivers on development velocity.

Instagram started with Django back in 2010, and they were able to scale to 14 million users with only 3 engineers, demonstrating how a well-structured monolith can support massive growth without requiring a large team.

The development speed advantage comes from having everything in one place. As one analysis notes, when developing using a monolithic architecture, "the primary advantage is fast development speed due to the simplicity of having an application based on one code base."

Monoliths Offer Lower Initial Infrastructure Costs

Startups operate under severe financial constraints, and monolithic architecture offers significant cost advantages. A monolithic app typically runs as a single unit on a few instances, making infrastructure costs more predictable and manageable.

Microservices add more complexity compared to a monolith architecture. Each new microservice can have its own cost for test suite, deployment playbooks, hosting infrastructure, monitoring tools, etc.

Even Amazon, the cloud computing giant, discovered these cost realities. A much-discussed Amazon case study from the Prime Video team showed an example of reducing infrastructure costs by 90% by moving from a microservices architecture to a monolith.

Monoliths Enable Simpler Deployment and Debugging

Operational simplicity is crucial when you're a small team wearing multiple hats. Monolithic architecture works with a single executable file or directory, which eases deployment. Further, a monolithic architecture is easier to maintain because it uses less components. This translates directly into reduced operational overhead.

When something breaks at 3 AM, you're dealing with one application, one log file, and one deployment. Not a distributed system where each microservice has its own set of logs, which makes debugging more complicated, and a single business process can run across multiple machines, further complicating debugging.

Monoliths (Usually) Require Smaller Teams

Startups typically begin with small, versatile teams, and monolithic architecture is designed for exactly this scenario. If you are a startup with 2 to 5 developers, you don't need to deal with the complexity of the microservices architecture. The architecture matches the organizational reality.

Teams often wear multiple hats, handling everything from database management to user interface design. This generalist approach works well with monoliths where all components are housed in one codebase, making development and deployment processes straightforward and easier for smaller teams.

Monolith Application Success Stories

Some of today's biggest companies started with monolithic architectures:

• Shopify - started as a monolithic Ruby on Rails application because they wanted to keep it simple and reduce costs. Even today, Shopify fully embraces the idea of a Majestic Monolith. Most user-facing functionality people tend to associate with the company is served by a single large Ruby on Rails application.

• Twitter - long before it became X, Twitter's story began like many startups of the mid-2000s. A small team with a big idea and Ruby on Rails as their technology of choice. Rails offered rapid development, elegant code structure, and the ability to ship features quickly. Twitter was created by a 2-man operation, and the first version was built in a few days.

When Monolithic Architecture Becomes a Limitation

Understanding when to evolve beyond a monolith is as important as knowing when to start with one. The limitations typically emerge around team size and feature complexity.

Research shows that microservices benefits are greatest with teams greater than 10 developers. Below this, monoliths perform better. As the system grows, it can no longer be maintained by a single team of a handful of developers, so extra teams are formed, creating coordination challenges.

As more features are added, the codebase grows in complexity, making it difficult for developers to understand and modify the application without unintended side effects. Changing one piece of code would cause unintended side effects on seemingly unrelated code, and building and testing the application took too long.

With the entire application bundled as a single unit, even minor changes can require full redeployments, leading to potential downtime and slower release cycles.

The key insight from successful companies is timing. As Shopify's engineering team noted, "the best time to refactor and re-architect is as late as possible, as you are constantly learning more about your system and business domain as you build."

When Do Large Enterprises Benefit from Microservices?

Enterprises choose microservices to enable independent team scaling, reduce deployment risks, and handle complex business domains - but only when they have the resources to manage increased operational complexity.

Large enterprises adopt microservices because they solve specific organizational and technical problems that monolithic architectures can't handle at scale. 

Microservices Offer Team Autonomy and Parallel Development

The most compelling business case for microservices is their ability to unlock team productivity at enterprise scale. There are many teams but they can stay small, eliminating the communication overhead that kills productivity in larger groups.

Teams don’t have to wait for others to finish something, they can focus on their part of the system. This parallel development leads to engineers being able to deploy code more often - which would be impossible with a monolithic architecture where any change requires rebuilding and testing the entire application.

Microservices Enable Risk Isolation and Operational Resilience

For enterprises where downtime costs thousands of dollars per minute, microservices provide crucial risk isolation. In a microservices architecture, if one service encounters a fault or failure, it doesn't propagate across the entire system. This compartmentalization means that, for example, when your payment service experiences issues, your product catalog and user authentication can continue operating normally.

AWS describes this as fault isolation: "If an individual microservice becomes unavailable, it doesn't disrupt the entire application as long as any upstream microservices are designed to handle faults correctly." This architectural pattern allows enterprises to maintain service availability even during partial system failures.

The business continuity implications are significant. Rather than losing all revenue during an outage, enterprises can maintain partial functionality and continue serving customers. This is particularly valuable for e-commerce platforms, financial services, and SaaS applications where availability directly impacts revenue.

Microservices Foster Technology Diversity and Innovation

Microservices enable what technologists call "polyglot programming"—the freedom for teams to choose the best technology stack for each specific job. While this might sound like a technical detail, it has profound business implications for enterprise innovation and talent retention.

Teams can use different stacks and programming languages for different components, allowing enterprises to adopt cutting-edge technologies without requiring a company-wide technology migration. A machine learning team can use Python and TensorFlow for recommendation algorithms while the billing team continues using Java and established enterprise frameworks.

This flexibility helps enterprises attract and retain top talent who want to work with modern technologies. It also enables faster adoption of new tools and frameworks as market conditions change, providing a competitive advantage in rapidly evolving industries.

Microservices Prerequisites

The benefits of microservices come with significant prerequisites that can’t be underestimated. Martin Fowler, one of the most respected voices in software architecture, identifies three fundamental capabilities that enterprises must have before attempting microservices:

1. Rapid Provisioning - you should be able to fire up a new server in a matter of hours. This requires substantial automation and typically cloud infrastructure capabilities.

2. Basic Monitoring - with many loosely-coupled services collaborating in production, things are bound to go wrong in ways that are difficult to detect in test environments. This calls for comprehensive monitoring for both technical issues and business metrics.

3. Rapid Application Deployment - you need to be able to quickly deploy services, both to test environments and to production, usually involving a deployment pipeline that can execute in no more than a couple of hours.

These capabilities require what Fowler calls "an important organizational shift - close collaboration between developers and operations."

As one engineer put it: "If you need to deliver fast and you're not yet into continuous delivery and DevOps, stay away from microservices." The architecture rewards enterprises that invest in the prerequisites but punishes those who adopt it prematurely.

What Are the Hidden Costs of Monoliths and Microservices That Most Managers Don't Consider?

Microservices can triple your operational complexity and infrastructure costs, while monoliths may create expensive technical debt that becomes harder to resolve over time.

Both architectural approaches carry significant hidden costs that often blindside business leaders who focus primarily on the technical benefits. These costs extend far beyond server bills and can dramatically impact your bottom line, team productivity, and long-term strategic flexibility.

Microservices Hidden Costs

The promise of microservices is tempting. Independent scaling, faster deployments, team autonomy; but it comes with a price tag that organizations should be aware of.

• Infrastructure explosion - each microservice introduces new infrastructure costs

• Network complexity and latency - microservices introduce network latency, serialization/deserialization overhead, and a larger attack surface due to multiple API endpoints

• Debugging nightmares - perhaps most challenging is the huge communication overhead both within the system and the engineering teams themselves. Each microservice has its own set of logs, which makes debugging more complicated. A single business process can run across multiple machines, further complicating debugging. 

• Team coordination complexity - teams need to add another level of communication and collaboration to coordinate updates and interfaces. Worst-case scenario: daily cross-team syncs for API changes and careful orchestration of deployments across multiple services.

Monolithic Hidden Costs

While monoliths are simpler initially, they accumulate hidden costs that compound over time, particularly as organizations scale.

• Deployment bottlenecks - a small change to a monolithic application requires the redeployment of the entire monolith. 

• Technology lock-in risks - monolithic applications are usually built using a single technology stack, meaning developers are stuck with the same programming languages, frameworks, and databases throughout the application's lifecycle, even if better technologies become available.

• Scaling limitations - because the entire application must be scaled at once, scaling a monolithic application can be difficult and lead to inefficiencies and higher resource usage.

• Refactoring costs - companies might face rewrite projects when their monoliths become unmanageable, requiring investment in re-architecting while maintaining business continuity.

Remember: the most expensive architecture decision is the one that forces a costly migration later. Plan for the hidden costs upfront, and choose the approach that aligns with your organization's real capabilities, not just your aspirations.

What Questions Should Guide Your Monolith vs Microservices Decision?

Before choosing your architecture, honestly assess:

• Your current team size and coordination capabilities

• Your time-to-market requirements

• Your infrastructure budget and operational expertise

• Your business domain complexity

• Your tolerance for complexity versus technical debt

• Your timeline for realizing benefits versus paying costs

• Your available technical expertise and organizational maturity

Any architecture has trade-offs that must be evaluated according to the context in which it's used.

Monolith Red Flags

• Multiple teams making frequent changes to the same codebase, causing merge conflicts and deployment bottlenecks

• Single points of failure affecting the entire application's availability

• Technology constraints preventing adoption of new frameworks or programming languages

• Scaling issues where the entire application must be scaled even when only specific components need additional resources

Microservices Red Flags

• Teams lacking experience with distributed systems, container orchestration, or service mesh technologies

• Absence of automated CI/CD pipelines and infrastructure as code practices

• Poorly defined domain boundaries or business capabilities that change frequently

• Limited operational budget for managing distributed systems complexity

How Do You Confirm That You Chose The Right Architecture?

Architecture should enable faster feature delivery and better customer experiences, not just satisfy technical elegance. You can track metrics like:

• lead time, 

• cycle time, 

• deployment frequency, 

• change failure rate, 

• mean time to recovery. 

These help you evaluate whether architectural changes actually improve your ability to deliver value.

Business alignment metrics are equally important. Analyze how well each component supports user needs, solves user problems, and delivers measurable outcomes. 

But the most important success metric? Whether your architecture reduces time-to-market while maintaining system reliability. If architectural complexity slows down feature delivery without proportional benefits, it's time to reconsider your approach.

Remember, the best time to refactor and re-architect is as late as possible, as you're constantly learning more about your system and business domain as you build. Don't rush into complexity. Let business needs and team growth guide your evolution.