Build vs. Buy: When to Use Workday Extend (2026)

Every organization faces the same question when a business process needs software support: do we buy a third-party SaaS tool, build a custom Workday Extend application, or use a pre-built Workday Marketplace application? The answer depends on several factors — and getting it wrong is expensive. This guide provides a framework for making the right decision.

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What Is the Build vs. Buy Decision in Workday?

The build vs. buy decision in the context of Workday is a three-way choice:

1. Buy a third-party SaaS tool and integrate it with Workday
2. Build a custom Workday Extend application using Workday's development platform
3. Buy a pre-built Workday Marketplace application built by a Workday partner

Each option has different costs, timelines, maintenance requirements, and strategic implications. The right choice depends on the specific use case, the organization's Workday maturity, and the long-term strategic direction.

For background on Workday Extend's capabilities, see our What Is Workday Extend guide.

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Key Concepts

Total Cost of Ownership (TCO): The full cost of a software solution over its lifetime, including licensing, implementation, integration, maintenance, and user training. Third-party SaaS tools often have lower initial costs but higher TCO due to integration and maintenance costs.

Integration Tax: The ongoing cost of maintaining an integration between a third-party tool and Workday. Every integration requires maintenance when Workday releases updates, when the third-party tool releases updates, and when business requirements change.

Workday Marketplace: The distribution channel for pre-built Workday Extend applications. Marketplace applications are built by Workday partners and are available for purchase by any Workday customer.

Workday Extend Studio: The development environment for building custom Workday Extend applications.

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The Decision Framework

Choose a Third-Party SaaS Tool When:

• The functionality required is complex and specialized (e.g., a full-featured CRM, a dedicated ERP for a specific industry)
• The third-party tool is the market standard for the use case and has deep functionality that would take years to replicate
• The integration between the third-party tool and Workday is simple and stable
• The organization does not have Workday Extend development skills and does not plan to invest in them

Examples: Salesforce for CRM, ServiceNow for ITSM, Coupa for procurement, Anaplan for financial planning.

Choose a Workday Marketplace Application When:

• The use case is common enough that a pre-built solution exists
• The pre-built solution covers 80%+ of the requirements without customization
• Speed of deployment is a priority
• The organization wants to minimize development investment

Examples: AssistNow's 11 Workday Marketplace applications cover equipment management, compliance tracking, capital project management, and more. Check the Marketplace before building.

Build a Custom Workday Extend Application When:

• The use case is unique to the organization and no pre-built solution exists
• The functionality is tightly integrated with Workday data and workflows
• The organization wants to eliminate a third-party tool and its integration
• The organization has Workday Extend development skills or is willing to invest in a partner to build and maintain the application

Examples: A custom capital project approval workflow that follows the organization's specific governance requirements, a compliance tracking application for a highly regulated industry with unique certification requirements.

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The Integration Tax Calculation

One of the most important factors in the build vs. buy decision is the integration tax — the ongoing cost of maintaining a third-party tool's integration with Workday.

A typical Workday integration costs $5,000–$20,000 to build and $2,000–$5,000 per year to maintain. Over five years, a single integration costs $15,000–$45,000 in maintenance alone. If a Workday Extend application can eliminate that integration, the savings can offset a significant portion of the development cost.

The integration tax is higher when:

• The integration is complex (bidirectional, real-time, with complex transformation logic)
• Workday releases updates that affect the integration (twice per year)
• The third-party tool releases updates that affect the integration
• The business requirements change, requiring integration modifications

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Best Practices

Calculate the five-year TCO for each option. Before making the build vs. buy decision, calculate the five-year total cost of ownership for each option. Include licensing, implementation, integration, maintenance, and training costs.

Check the Workday Marketplace first. Before investing in a custom build, check whether a pre-built Marketplace application covers the use case. AssistNow and other Workday partners have built applications for many common use cases.

Consider the integration tax. If the third-party tool requires a complex Workday integration, factor the integration tax into the TCO calculation. The integration tax often makes Workday Extend applications more cost-effective than they initially appear.

Assess organizational readiness. Building a Workday Extend application requires either internal development skills or a trusted partner. Assess whether the organization has the skills and capacity to build and maintain a custom application before committing to the build option.

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Frequently Asked Questions

Is Workday Extend always cheaper than a third-party SaaS tool? Not always. For complex, specialized functionality, a third-party SaaS tool with deep functionality may be more cost-effective than building a custom Workday Extend application. The key is to calculate the five-year TCO for each option, including integration costs.

How do we find Workday Marketplace applications? The Workday Marketplace is accessible through the Workday Community portal. You can search by use case, industry, or partner. AssistNow's 11 applications are listed in the Marketplace under the AssistNow partner profile.

What happens if our Workday Extend application breaks after a Workday update? Workday provides advance notice of changes that may affect Workday Extend applications. Organizations should test their Extend applications in a sandbox tenant before each Workday update is applied to production. Applications purchased from the Workday Marketplace are maintained by the publisher.

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Key Takeaways

• The build vs. buy decision in Workday is a three-way choice: third-party SaaS, custom Workday Extend, or Workday Marketplace application.
• Choose a third-party SaaS tool for complex, specialized functionality where a market-standard solution exists.
• Choose a Workday Marketplace application when a pre-built solution covers the use case.
• Choose a custom Workday Extend application for unique use cases tightly integrated with Workday data.
• The integration tax — the ongoing cost of maintaining a third-party tool's Workday integration — often makes Workday Extend applications more cost-effective than they initially appear.

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AssistNow helps organizations evaluate build vs. buy decisions for Workday Extend. Contact us to discuss your use case.