If you’ve ever browsed the Slack Marketplace or explored your workspace’s “Apps” section, you’ve likely seen the terms “Slack app” and “Slack integration” used—often interchangeably. This creates a common point of confusion. Are they the same thing? If not, what separates them? Understanding this distinction is more than semantic; it’s key to grasping the architecture of the Slack platform and making informed decisions about how you connect tools to your workspace.
The short answer is: All integrations are built as Slack apps, but not all Slack apps are what users traditionally think of as third-party integrations.
The Evolution of Terminology: From “Integrations” to “Slack Apps”
To understand the present, we must look at the past. In Slack’s early days, the term “integration” was the catch-all phrase. It described any connection that brought information from an external service (like Google Drive notifications or GitHub commits) into Slack. These were often simple, one-way webhook connections that posted messages to a channel.
As the platform matured, Slack introduced a more robust, secure, and capable development framework. This shift brought about the formal, technical concept of a “Slack app.” A Slack app is any piece of software that interacts with the Slack platform through its official APIs (Application Programming Interfaces). This is a crucial platform evolution:
- “Integration” became the user-facing, functional description—it’s what the software does (it integrates Tool X with Slack).
- “Slack app” became the official, technical designation—it’s what the software is (an application built on Slack’s platform).
Today, Slack’s official documentation and developer resources almost exclusively use the term “Slack app.” However, the word “integration” persists in everyday conversation because it perfectly describes the user’s experience and intent. Think of it like this: “WhatsApp” is a messaging app, but its function is to provide communication. “App” describes its form; “communication” describes its function.
The Unified Foundation: The Slack Platform
The core technical truth that unifies these terms is the Slack Platform. Every single connection into Slack—whether a simple incoming webhook, a complex bot, or a full-featured suite like Asana or Salesforce—is built as a Slack app and utilizes the same foundational building blocks:
- The Slack API: The set of protocols and tools that allows external software to communicate securely with Slack.
- Scopes & OAuth: The permission system. When you click “Allow,” you grant the app specific OAuth scopes (like
chat:writeto post messages orchannels:readto view channel lists). - Manifest: A configuration file that defines the app’s name, permissions, features, and setup instructions.
Therefore, from a developer’s and Slack’s infrastructure perspective, there is only one entity: the Slack app. The term “integration” has been absorbed into this model as a primary use case for an app.
Deconstructing the Categories: Types of Slack Apps
The confusion often arises because “Slack app” encompasses several different types of software, which serve vastly different purposes. We can break them down into three primary categories.
1. Published Apps (The Classic “Integration”)
These are the most recognizable. They are third-party, publicly available applications built by other companies (like Google, Zoom, or Asana) or independent developers and listed in the Slack Marketplace. When a user searches for “Trello integration,” they find and install the “Trello for Slack” app.
Key Characteristics:
- Purpose: To connect a separate, established SaaS product with Slack.
- Development: Built and maintained by the external company (e.g., Atlassian builds the Trello for Slack app).
- Discovery: Found in the public Slack Marketplace.
- User Experience: Installed with a few clicks, requiring user authentication with the third-party service.
2. Internal or Custom Apps (The Hidden Powerhouse)
These are Slack apps built internally by an organization’s own developers, tailored to their unique workflows. They are not published to the public Marketplace and are only available within that specific workspace or Enterprise Grid organization.
Key Characteristics:
- Purpose: To automate internal processes, connect to proprietary tools, or create custom commands and workflows.
- Development: Built in-house by the organization’s IT or development teams using Slack’s Bolt framework and APIs.
- Discovery: Not discovered publicly; they are built for a specific need (e.g., an app that queries the internal HR database via a Slack command like
/find-employee). - User Experience: They feel like a native part of the company’s Slack workspace. They often use custom slash commands (e.g.,
/expense-report) or interact with workflow builder.
3. Slack’s Native “Feature Apps”
This is a subtle but important category. Some functionality that feels built directly into Slack is technically implemented as internal Slack apps. The most prominent example is Workflow Builder. While it feels like a core feature, it is an app that provides a no-code interface to automate tasks. Another example could be the Slack AI summary feature, which operates as an app-like service within the platform.
Practical Implications: A Decision Matrix
Understanding this distinction directly impacts what you build or implement. Here’s a guide:
| Consideration | Published (Marketplace) App | Internal/Custom App |
|---|---|---|
| When to Choose | When using a popular third-party tool (Google, Salesforce, etc.). When you need a standard, supported connection. | When automating a unique, internal business process. When connecting to proprietary/internal software. When public apps don’t meet your security or functional needs. |
| Development & Maintenance | Maintained by the third-party vendor. Your team is not responsible for code updates related to API changes. | Your team is fully responsible for development, security, maintenance, and updates based on Slack API changes. |
| Control & Security | You trust the vendor’s security practices. You grant permissions they define. | You have full control over the code, data handling, and permissions (scopes). Ideal for sensitive internal data. |
| Cost | Often freemium; premium features may require a subscription to the external service or the app itself. | Cost is internal developer time and resources (build, maintain, secure). |
Why This Distinction Matters for Your Workspace
- For Admins & Security: Understanding that every connection is a “Slack app” governed by OAuth scopes is crucial for security. An admin must audit both Marketplace apps and custom internal apps in Settings & Administration > Manage apps. A poorly secured internal app can pose as much risk as a malicious third-party one.
- For Developers: The developer journey is unified. Whether building for the public Marketplace or for internal use, you use the same Slack API, Bolt framework, and deployment tools. The choice is about distribution, not foundation.
- For Users & Decision-Makers: When a team requests “an integration,” you must diagnose: Is this a request to install a pre-built app from the Marketplace (fast, low maintenance), or is it a request for a custom software project to build an internal app (powerful, but requires dev resources)? This clarity prevents misaligned expectations.
Conclusion: Two Sides of the Same Coin
In the end, “Slack app” is the formal, encompassing category of software built on the Slack platform. “Integration” is the functional outcome that most of these apps deliver—the act of connecting services and data to Slack.
- If you are a user wanting to connect Trello, you want the Trello for Slack (a published app) to achieve integration.
- If you are a developer automating your company’s stand-up reports, you are building a custom internal Slack app that integrates your reminder system with Slack.
By embracing this nuanced understanding, you move from casual user to informed architect of your digital workspace. You can better communicate needs, assess security, allocate development resources, and ultimately leverage the full, powerful spectrum of the Slack Platform—from simple, off-the-shelf integrations to complex, custom-built automation engines that make your workspace uniquely efficient.