Protect website users without slowing down business

Fastly Client-Side Protection

Prevent theft and misuse of customer data with a complete set of tools for script inventory and management.
You’ll be able to fully document, understand, and manage your client-side attack surfaces in real time to stop client-side attacks and meet your compliance objectives.

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Benefits

Defend against client-side attacks

Vulnerabilities in third-party scripts can lead to security gaps in your web applications and dangers like payment card skimming (Magecart) attacks. Fastly Client-Side Protection provides a simple set of tools to monitor scripts on pages and control what is loaded and executed in user browsers to protect websites and users from client-side attacks.

Inventory

Build a comprehensive inventory of your pages, third-party scripts and business or technical justifications for their use, in minutes.
Reporting and Alerting

Monitor third-party scripts in real time and detect unauthorized activity, and generate alerts on any unauthorized or malicious scripts.
Compliance

Meet your industry-specific compliance objectives and address requirements for client-side security measures.

Looking for more?

Fastly Client-Side Protection
Fastly Client-Side Protection provides script inventory and management to defend against client-side exploits and helps your organization meet certain PCI-DSS 4.0 requirements.
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Addressing PCI DSS 4.0 and Requirement 6.4.2
PCI DSS 4.0 requires organizations to procure and deploy a WAF by March 25, 2025.
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Schellman Review: Fastly Client-Side Protection
This whitepaper evaluates Fastly Client-Side Protection and its capabilities in helping organizations meet applicable PCI DSS 4.0.1 requirements.
Read the Whitepaper

Frequently Asked Questions

What is client side protection and why does it matter?

Client side protection secures the browser environment where your users interact with your application. While traditional security tools focus on servers and APIs, attackers increasingly target third-party JavaScript, payment forms, and other client-side components.

Fastly Client-Side Protection helps detect malicious activity in the browser, including script tampering, Magecart-style attacks, and data exfiltration. For security leaders and engineers, this closes a visibility gap that server-side controls alone cannot address.

How does Fastly Client-Side Protection help with PCI compliance?

Fastly Client-Side Protection supports PCI compliance by monitoring and controlling scripts that handle payment data in the browser. It provides visibility into third-party and first-party JavaScript behavior, helping teams meet PCI DSS requirements around script integrity and change detection.

For organizations working with a PCI compliance manager, this added layer of client security helps reduce audit friction and strengthens documentation around payment page protection.

How is client security different from traditional web application security?

Traditional web application security focuses on protecting servers, APIs, and infrastructure. Client security focuses on what happens in the user’s browser.

Client-side attacks can bypass server-side defenses by injecting or modifying scripts after the page loads. Fastly Client-Side Protection monitors script behavior in real time, detects unauthorized changes, and flags malicious activity before sensitive data is exposed.

For engineering and platform teams, this provides end-to-end coverage from edge to browser.

Can Fastly Client-Side Protection detect malicious third-party scripts?

Yes. Third-party scripts are one of the most common sources of client-side risk.

Fastly Client-Side Protection continuously analyzes script behavior in the browser and identifies unexpected or malicious activity, including data collection attempts and unauthorized network calls. This allows teams to safely leverage third-party services while maintaining strong client security controls.

Does implementing client side protection impact performance?

Client side protection should not come at the cost of user experience.

Fastly is built to operate at the edge with minimal latency. Client-side monitoring is designed to integrate into existing workflows and performance strategies, so teams can strengthen client security without slowing down their applications.

For organizations, this means improving visibility and compliance posture while maintaining the speed and reliability users expect.

Ready to check compliance off your to-do list?

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