From ACS to Azure AD App Registrations: Why Now Is the Right Time to Modernize SharePoint Access
Many SharePoint apps still rely on outdated Access Control Services (ACS) — often unknowingly. In this article, we explain why Azure AD App Registrations are the modern, secure alternative and how to make the switch safely
Jul 16, 2025
Jul 16, 2025
5 min.
5 min.
Author
Tim Lauenroth
Product Marketing Manager
Still using Access Control Services (ACS) for SharePoint? It’s time to modernize.
Many companies still rely on Access Control Services (ACS) to let their SharePoint applications access content — often without realizing it. But ACS is outdated, sometimes even risky. Microsoft now recommends a more secure and future-proof solution: Azure AD App Registrations.
In this article, we’ll explain:
What ACS is and why it was used
Why it’s now considered a risk
What Azure AD offers as a better alternative
And how we can help you make the switch — safely and smoothly.
What is ACS — and why was it used in the first place?
Access Control Services (ACS) was introduced by Microsoft as an authentication service that allowed apps to communicate with SharePoint — even without any user interaction. This “app-only access” model was especially useful for
Third-party apps pulling data from SharePoint
Background jobs moving files between libraries
Internal tools writing directly to SharePoint lists
At the time, ACS-based access was pretty innovative. But things have changed — and fast.
Why ACS is a problem today
Yes, ACS still technically works. But Microsoft no longer develops it — and strongly recommends moving away from it. Why? Let’s break it down:
Outdated security
No conditional access, no MFA, no role-based access control.
No central management
Many apps run silently in the background — no one knows when their tokens expire or what access they have.
Increased attack surface
Old secrets, overly broad permissions, no audit trail.
Uncertain future
ACS is deprecated. It won’t get new features, and support could disappear anytime.
If you register an app today, Azure AD is the default. ACS belongs to the past.
The modern way: Azure AD App Registrations
Azure Active Directory (Azure AD) gives you a secure, central, and future-proof way to connect apps to Microsoft 365. Here’s how it compares to ACS:
ACS (Legacy) | Azure AD (Modern) | |
|---|---|---|
Management | Manually in SharePoint | Centrally in Azure Portal |
Security | Basic Auth + Tokens | MFA, Conditional Access, RBAC |
Token Handling | SAML, static | JWT, dynamic, with expiration control |
Visibility | No app overview | Full transparency |
Microsoft Support | Deprecated | Future-proof |
We make the switch possible — smooth & secure
Switching from ACS to Azure AD isn’t just a one-click job. It takes deep knowledge of:
Token flows and authentication models
SharePoint permissions and app scopes
Azure AD App Registrations and secret handling
Existing workflow dependencies
👉 That’s where we come in.
We’ll help you identify which apps are still using ACS, assess their risk level, and set up a secure Azure AD-based structure.
Whether you’re using REST APIs, PowerShell scripts, or third-party integrations — we know the pitfalls, and we know how to avoid them.
Why now is the perfect time
Every organization has to modernize legacy systems sooner or later — without disrupting current operations. Migrating from ACS to Azure AD is a perfect example of this.
Here’s why you shouldn’t wait:
The longer ACS runs, the higher the risk — expired tokens, system failures, security breaches
More integrations = more reliance on outdated technology
The industry is moving forward — modernizing now means being ready for what’s next
That’s why now is exactly the right time to act.
Common questions companies ask us
“We’re not even sure we use ACS — can you check?”
“Our app suddenly stopped working — could it be token-related?”
“We want to modernize our automations — is Azure AD a safe choice?”
“We don’t have the capacity internally — can you help?”
✅ Our answer: Yes, we’ve got you covered.
Want to know if you’re affected — and how to migrate safely?
Let’s get you some clarity:
Analysis: We check your tenant for any ACS-based access
Execution: We create a secure migration plan and implement it with you
Security: We set up maintainable, auditable Azure AD App Registrations
👉 Reach out now and book a free consultation.
Still using Access Control Services (ACS) for SharePoint? It’s time to modernize.
Many companies still rely on Access Control Services (ACS) to let their SharePoint applications access content — often without realizing it. But ACS is outdated, sometimes even risky. Microsoft now recommends a more secure and future-proof solution: Azure AD App Registrations.
In this article, we’ll explain:
What ACS is and why it was used
Why it’s now considered a risk
What Azure AD offers as a better alternative
And how we can help you make the switch — safely and smoothly.
What is ACS — and why was it used in the first place?
Access Control Services (ACS) was introduced by Microsoft as an authentication service that allowed apps to communicate with SharePoint — even without any user interaction. This “app-only access” model was especially useful for
Third-party apps pulling data from SharePoint
Background jobs moving files between libraries
Internal tools writing directly to SharePoint lists
At the time, ACS-based access was pretty innovative. But things have changed — and fast.
Why ACS is a problem today
Yes, ACS still technically works. But Microsoft no longer develops it — and strongly recommends moving away from it. Why? Let’s break it down:
Outdated security
No conditional access, no MFA, no role-based access control.
No central management
Many apps run silently in the background — no one knows when their tokens expire or what access they have.
Increased attack surface
Old secrets, overly broad permissions, no audit trail.
Uncertain future
ACS is deprecated. It won’t get new features, and support could disappear anytime.
If you register an app today, Azure AD is the default. ACS belongs to the past.
The modern way: Azure AD App Registrations
Azure Active Directory (Azure AD) gives you a secure, central, and future-proof way to connect apps to Microsoft 365. Here’s how it compares to ACS:
ACS (Legacy) | Azure AD (Modern) | |
|---|---|---|
Management | Manually in SharePoint | Centrally in Azure Portal |
Security | Basic Auth + Tokens | MFA, Conditional Access, RBAC |
Token Handling | SAML, static | JWT, dynamic, with expiration control |
Visibility | No app overview | Full transparency |
Microsoft Support | Deprecated | Future-proof |
We make the switch possible — smooth & secure
Switching from ACS to Azure AD isn’t just a one-click job. It takes deep knowledge of:
Token flows and authentication models
SharePoint permissions and app scopes
Azure AD App Registrations and secret handling
Existing workflow dependencies
👉 That’s where we come in.
We’ll help you identify which apps are still using ACS, assess their risk level, and set up a secure Azure AD-based structure.
Whether you’re using REST APIs, PowerShell scripts, or third-party integrations — we know the pitfalls, and we know how to avoid them.
Why now is the perfect time
Every organization has to modernize legacy systems sooner or later — without disrupting current operations. Migrating from ACS to Azure AD is a perfect example of this.
Here’s why you shouldn’t wait:
The longer ACS runs, the higher the risk — expired tokens, system failures, security breaches
More integrations = more reliance on outdated technology
The industry is moving forward — modernizing now means being ready for what’s next
That’s why now is exactly the right time to act.
Common questions companies ask us
“We’re not even sure we use ACS — can you check?”
“Our app suddenly stopped working — could it be token-related?”
“We want to modernize our automations — is Azure AD a safe choice?”
“We don’t have the capacity internally — can you help?”
✅ Our answer: Yes, we’ve got you covered.
Want to know if you’re affected — and how to migrate safely?
Let’s get you some clarity:
Analysis: We check your tenant for any ACS-based access
Execution: We create a secure migration plan and implement it with you
Security: We set up maintainable, auditable Azure AD App Registrations
👉 Reach out now and book a free consultation.
Still using Access Control Services (ACS) for SharePoint? It’s time to modernize.
Many companies still rely on Access Control Services (ACS) to let their SharePoint applications access content — often without realizing it. But ACS is outdated, sometimes even risky. Microsoft now recommends a more secure and future-proof solution: Azure AD App Registrations.
In this article, we’ll explain:
What ACS is and why it was used
Why it’s now considered a risk
What Azure AD offers as a better alternative
And how we can help you make the switch — safely and smoothly.
What is ACS — and why was it used in the first place?
Access Control Services (ACS) was introduced by Microsoft as an authentication service that allowed apps to communicate with SharePoint — even without any user interaction. This “app-only access” model was especially useful for
Third-party apps pulling data from SharePoint
Background jobs moving files between libraries
Internal tools writing directly to SharePoint lists
At the time, ACS-based access was pretty innovative. But things have changed — and fast.
Why ACS is a problem today
Yes, ACS still technically works. But Microsoft no longer develops it — and strongly recommends moving away from it. Why? Let’s break it down:
Outdated security
No conditional access, no MFA, no role-based access control.
No central management
Many apps run silently in the background — no one knows when their tokens expire or what access they have.
Increased attack surface
Old secrets, overly broad permissions, no audit trail.
Uncertain future
ACS is deprecated. It won’t get new features, and support could disappear anytime.
If you register an app today, Azure AD is the default. ACS belongs to the past.
The modern way: Azure AD App Registrations
Azure Active Directory (Azure AD) gives you a secure, central, and future-proof way to connect apps to Microsoft 365. Here’s how it compares to ACS:
ACS (Legacy) | Azure AD (Modern) | |
|---|---|---|
Management | Manually in SharePoint | Centrally in Azure Portal |
Security | Basic Auth + Tokens | MFA, Conditional Access, RBAC |
Token Handling | SAML, static | JWT, dynamic, with expiration control |
Visibility | No app overview | Full transparency |
Microsoft Support | Deprecated | Future-proof |
We make the switch possible — smooth & secure
Switching from ACS to Azure AD isn’t just a one-click job. It takes deep knowledge of:
Token flows and authentication models
SharePoint permissions and app scopes
Azure AD App Registrations and secret handling
Existing workflow dependencies
👉 That’s where we come in.
We’ll help you identify which apps are still using ACS, assess their risk level, and set up a secure Azure AD-based structure.
Whether you’re using REST APIs, PowerShell scripts, or third-party integrations — we know the pitfalls, and we know how to avoid them.
Why now is the perfect time
Every organization has to modernize legacy systems sooner or later — without disrupting current operations. Migrating from ACS to Azure AD is a perfect example of this.
Here’s why you shouldn’t wait:
The longer ACS runs, the higher the risk — expired tokens, system failures, security breaches
More integrations = more reliance on outdated technology
The industry is moving forward — modernizing now means being ready for what’s next
That’s why now is exactly the right time to act.
Common questions companies ask us
“We’re not even sure we use ACS — can you check?”
“Our app suddenly stopped working — could it be token-related?”
“We want to modernize our automations — is Azure AD a safe choice?”
“We don’t have the capacity internally — can you help?”
✅ Our answer: Yes, we’ve got you covered.
Want to know if you’re affected — and how to migrate safely?
Let’s get you some clarity:
Analysis: We check your tenant for any ACS-based access
Execution: We create a secure migration plan and implement it with you
Security: We set up maintainable, auditable Azure AD App Registrations
👉 Reach out now and book a free consultation.
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Register now and test timeghost Time Tracking for 14 days completely free of charge!
Simply invite team members and track work and project times in your familiar Microsoft working environment.
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Register now and test timeghost Time Tracking for 14 days completely free of charge!
Simply invite team members and track work and project times in your familiar Microsoft working environment.
