How to Map Your SaaS Dependencies

Most businesses can name the five or six SaaS tools they use daily. Slack, Google Workspace, Stripe, maybe HubSpot and Jira. But when you sit down and actually inventory every third-party service your operations touch, the number is usually three to five times higher than anyone expected.

According to Gartner's research on SaaS management, the average mid-size company uses between 80 and 150 SaaS applications. Many of those operate in the background, invisible until they break. That invisible dependency is exactly what makes SaaS outages so disruptive. You cannot prepare for a failure you do not know exists.

Dependency mapping is the process of identifying every SaaS service your business relies on, understanding how they connect to each other and to your operations, and categorizing them by criticality. It is the foundation of effective vendor management and incident response.

Why Mapping Matters

There are three practical reasons to map your SaaS dependencies, and none of them are theoretical.

Faster Incident Response

When a vendor goes down, the first question is always "what does this affect?" Without a dependency map, your team spends the first 15 to 30 minutes of an outage figuring out the blast radius. With a map, you know immediately which workflows, teams, and customer-facing features are impacted. Our vendor outage response playbook depends on this knowledge being available before the outage happens.

Informed Vendor Decisions

When you can see all your dependencies in one place, patterns emerge. You might discover that three critical workflows all depend on the same vendor, creating a single point of failure. Or that you are paying for two tools that do the same thing. Or that a vendor you considered low-risk actually underpins your payment processing chain. Dependency mapping gives you the visibility to make better vendor selection decisions.

Reduced Downtime Costs

The cost of vendor downtime multiplies when you do not understand your dependency chain. A Twilio outage is annoying if it only affects your notification system. It is a crisis if it also breaks your two-factor authentication flow and your customer support callback system. Knowing these connections in advance lets you build redundancy where it matters most.

How to Identify All Your Dependencies

The hardest part of dependency mapping is the identification phase. SaaS dependencies hide in places you do not expect.

Direct Dependencies

These are the obvious ones. Services your team actively logs into and uses throughout the day. Think Slack, GitHub, Figma, Salesforce, Notion. Start by surveying each team and asking: what tools do you use every day? What do you log into at least weekly?

Check your company's SSO provider or identity management system. If you use Okta, Google Workspace, or Azure AD, the list of connected applications is your starting point. It will not be complete, but it covers the tools that go through centralized authentication.

Review your expense reports and credit card statements. SaaS subscriptions leave a paper trail. Look for recurring charges to software vendors, especially small ones that might not be on anyone's radar.

Indirect Dependencies

These are trickier. Indirect dependencies are services that your direct dependencies rely on. You do not have an account with them, but your operations depend on them.

Your website might use Cloudflare for CDN and DDoS protection. Your email marketing tool might send through SendGrid. Your payment processor uses banking APIs under the hood. When any of these underlying services fail, your tools break even though you have no direct relationship with the failing service.

To find indirect dependencies, ask your engineering team: what third-party APIs do we call? What services are in our infrastructure stack? Check your DNS records for CNAME entries pointing to third-party services. Review your application's environment variables for API keys, each one represents a dependency.

Infrastructure Dependencies

These sit below everything else. Your cloud hosting provider (AWS, GCP, Azure), your DNS provider, your domain registrar, your CDN, your container registry. Infrastructure dependencies are easy to forget because they "just work" until they do not.

AWS's us-east-1 outage in December 2021 took down a staggering number of services precisely because so many companies treated it as invisible infrastructure rather than a dependency to plan around.

Do not forget about DNS as a hidden dependency. If your DNS provider goes down, nothing else matters because nobody can resolve your domain.

Building the Map

Once you have your list of dependencies, you need to organize them into something useful. There are two common formats, and the right one depends on your team size and complexity.

The Spreadsheet Approach

For most small and mid-size teams, a spreadsheet is the right starting point. Create a table with these columns:

Service name. The vendor's name (e.g., Stripe, Cloudflare, SendGrid).

Category. What type of service it is: communication, payments, infrastructure, analytics, development tools, etc.

Dependency type. Direct (your team uses it), indirect (something you use depends on it), or infrastructure (underlying platform).

Teams affected. Which internal teams are impacted when this service goes down.

Workflows affected. Specific business processes that depend on this service. Be concrete: "customer checkout," "employee onboarding," "deploy pipeline."

Criticality tier. How bad is it if this goes down? More on this in the next section.

Status page URL. Where to check during an outage. This is also what you will feed into your vendor monitoring setup.

Fallback plan. What your team does if this service is unavailable. Even if the answer is "wait for it to come back," write that down.

The Diagram Approach

For larger organizations or complex architectures, a visual diagram makes the relationships between services easier to understand. Tools like Miro, Lucidchart, or even a whiteboard work well.

Start with your customer-facing products at the top. Draw lines down to every service they depend on. Then draw lines from those services to their dependencies. You will end up with a tree (or more likely, a web) that shows exactly how a failure in any one service cascades through your operations.

The visual format is especially useful for identifying single points of failure. If multiple branches of your tree converge on a single service, that service is a critical risk regardless of how reliable it seems.

Categorizing by Criticality

Not all dependencies are equally important. Categorizing by criticality helps you focus monitoring and response efforts where they matter most.

Tier 1: Business Critical

If this service goes down, customer-facing operations stop or revenue is directly impacted. Examples: your payment processor, your hosting provider, your primary database, your authentication system.

Tier 1 services need real-time monitoring, immediate alerting, and documented fallback procedures. These are the services you monitor with a tool like Is That Down so you know the moment something changes.

Tier 2: Operations Critical

If this service goes down, internal operations are significantly disrupted, but customers may not notice immediately. Examples: your CI/CD pipeline, your internal communication tool, your project management system, your CRM.

Tier 2 services need monitoring and alerting, but the response can be less urgent. A 30-minute delay in your deploy pipeline is not a customer emergency.

Tier 3: Convenience

If this service goes down, it is annoying but work continues. Examples: your design tool, your time tracking app, your company wiki. These services are worth tracking but do not need urgent response procedures.

The tier assignment is not based on how much you like the tool. It is based on business impact. A team might love Notion, but if it goes down for two hours, work continues through other channels. Stripe going down for two hours means zero revenue.

Keeping the Map Updated

A dependency map is only useful if it reflects reality. SaaS stacks change constantly. Teams adopt new tools, cancel old subscriptions, and engineering adds new API integrations.

Quarterly reviews. Set a calendar reminder to review your dependency map every quarter. Send a quick survey to team leads asking if anything has changed. Check your SSO and billing records for new additions.

Change triggers. Any time your team adopts a new SaaS tool, adds a new API integration, or changes infrastructure providers, update the map. Make this part of your procurement or onboarding process.

Incident-driven updates. After any vendor outage, review whether the incident revealed dependencies you had not mapped. Outages are the best teacher. If a service you did not have on your map caused problems, add it immediately and assign a criticality tier.

Ownership. Assign a single person or team to own the dependency map. Without clear ownership, it will go stale within months. This is typically an IT, DevOps, or operations function.

Using the Map for Incident Response

The dependency map pays for itself the first time you have a vendor outage. Here is how to use it in practice.

When an alert fires. You get notified that a vendor is experiencing issues. Pull up your dependency map. Identify the criticality tier and all affected workflows. This tells you whether this is a "drop everything" situation or a "keep an eye on it" situation.

Assess the blast radius. Look at which teams and workflows depend on the affected service. Notify those teams immediately so they are not blindsided. Check for indirect dependencies: if AWS is down, which of your other vendors are also hosted on AWS?

Activate fallback plans. For Tier 1 services, your map should include documented fallbacks. Activate them. For Tier 2 and 3, communicate the expected impact and timeline.

Post-incident review. After the outage resolves, review how accurate your map was. Did you miss any affected workflows? Were the criticality tiers correct? Update the map based on what you learned.

For a complete incident response framework that builds on your dependency map, see our vendor outage response playbook.

Common Mistakes in Dependency Mapping

Stopping at direct dependencies. The services your team logs into are only the beginning. Indirect and infrastructure dependencies cause some of the worst outages because nobody saw them coming.

Treating it as a one-time project. A dependency map from six months ago is already wrong. Build update triggers into your process.

Ignoring the "boring" dependencies. DNS, SSL certificates, domain registration, CDN. These unglamorous infrastructure services underpin everything. Map them.

Not assigning criticality tiers. A flat list of 80 services is not actionable. Tiers tell your team what to care about first.

No fallback plans for Tier 1. If you know a service is business critical but your fallback plan is "hope it comes back soon," you have not finished the mapping exercise.

References

• Gartner - SaaS Management - Research on SaaS sprawl and management challenges in mid-market and enterprise organizations.
• AWS us-east-1 Outage Summary (2021) - Example of cascading infrastructure dependency failure.