5 Best RASP Tools (2026): Runtime Protection Reviewed

What is RASP?

The new era of application security firewalls starts with naming, Runtime Application Self-Protection.

This is not for scanning and finding vulnerabilities in applications.

This is for monitoring and blocking attacks in real-time.

Old friend web application firewalls usually sit in front of traffic and inspect all incoming HTTP requests and report/block if a suspicious pattern is detected. RASP tools will be integrated into the application and make decisions according to how the application will execute these requests.

Excellent to avoid false positives, but may cause performance issues as the RASP agent sits between the application and server.

The need for RASP has grown as web application attacks have exploded. According to industry reports, attacks on web applications increased by approximately 800% in the first half of 2020 compared to the same period in 2019. The RASP market reached $2.02 billion in 2025 and is forecast to grow to $7.17 billion by 2030 at a 28.82% CAGR (Mordor Intelligence). Over 64% of enterprises are now implementing runtime protection to handle sophisticated cyber threats.

“WAFs are like airport security — they check everyone at the gate but can’t stop threats once they’re on the plane,” explains Kunal Anand, former CTO of Imperva and current CTO of Fortanix. “RASP is the air marshal sitting in the cabin, watching what actually happens during the flight.”

Advantages

• No need to train or configure rules
• Context-aware blocking reduces false positives
• Protects against zero-day attacks
• Immediate protection while fixing vulnerabilities
• Detailed attack telemetry for forensics

Limitations

• Performance overhead (2-10% latency)
• Language dependent (agent support varies)
• Risk of over-reliance instead of fixing vulns
• False sense of security if misconfigured
• Deployment complexity for containerized apps

I have deployed RASP tools at financial services companies where false positive rates are unacceptable.

The key is starting in monitor mode, then moving to blocking once you trust the tool.

How RASP Works

RASP uses runtime instrumentation to detect attacks as they happen.

Here is the typical workflow:

Agent Installation

The RASP agent is installed into the application runtime (JVM, .NET CLR, Node.js, etc.) or loaded as a library. This happens once during deployment, either by modifying startup scripts or container images.

Function Hooking

The agent hooks into security-sensitive functions like SQL execution, file I/O, command execution, and network calls. These hooks intercept data before dangerous operations complete.

Context Analysis

When a hooked function is called, RASP analyzes the input against the code path to determine if it is an attack. Unlike WAFs, RASP sees whether untrusted data actually reaches dangerous functions.

Block or Report

Depending on your configuration, RASP either blocks the request immediately or logs it for review. Always start in monitor mode to understand baseline behavior before enabling blocking.

Quick Comparison of RASP Tools

Tool	USP	License
Free / Open Source
OpenRASP	Most popular open-source RASP, by Baidu	Open Source
Commercial
Contrast Protect	Part of Contrast Security platform	Commercial
Datadog ASM	RASP engine from Sqreen, APM integration	Commercial
Dynatrace	RASP module in Dynatrace platform	Commercial
Imperva RASP	Combines well with Imperva WAF	Commercial
Waratek	JVM-embedded, virtual patching	Commercial
Acquired
Signal Sciences	Acquired by Fastly → Next-Gen WAF	Commercial
K2 Cyber Security	Acquired by Contrast Security	Commercial
Deprecated
Hdiv Protection	No longer actively maintained	Commercial

RASP vs WAF

Both RASP and WAF (Web Application Firewall) protect applications at runtime, but they work differently.

Understanding when to use each helps you make better decisions.

Aspect	RASP	WAF
Location	Inside the application	In front of the application
Detection method	Code execution context	HTTP traffic patterns
False positives	Low (knows if input is dangerous)	Higher (pattern matching only)
Performance impact	2-10% latency added	Minimal (separate infrastructure)
Deployment	Per-application agent install	Network-level, all apps at once
Best for	High-value apps needing accuracy	Broad coverage, DDoS protection

My take: Use both if you can afford it. WAF provides perimeter defense and DDoS protection. RASP provides accurate, context-aware protection for your most critical applications. If you must choose one, WAF is the safer starting point because it requires no code changes.

Market Changes

The RASP market has seen significant consolidation:

Sqreen → Datadog (2021)

Datadog acquired Sqreen and integrated its RASP engine into Datadog Application Security Management (ASM). A strong option if you already use Datadog for APM.

Signal Sciences → Fastly (2020)

Signal Sciences was acquired by Fastly and became the foundation of Fastly's Next-Gen WAF. Still available but no longer sold as a standalone RASP.

K2 Cyber Security → Contrast (2021)

K2 Cyber Security was acquired by Contrast Security. Technology merged into Contrast Protect.

Hdiv Security (Deprecated)

Hdiv Protection is no longer actively maintained. If you are using it, consider migrating to another solution.

How to Choose a RASP Tool

The RASP market is small compared to other AppSec categories.

Here are the factors I consider when recommending a tool:

Language Support

Check if the tool supports your primary language. Java and .NET have the best coverage. Node.js and Python support varies. Go and Rust have almost no RASP options.

Performance Overhead

Run benchmarks in your environment. Some tools add 2% latency, others add 10%. For latency-sensitive services, this matters. Waratek claims minimal overhead due to its virtualization-based architecture.

Existing Security Stack

If you already use Contrast for SAST/IAST, Contrast Protect is an easy add. If you use Imperva WAF, their RASP integrates well. If you use Datadog for APM, their RASP module is already there.

Open-source vs Commercial

OpenRASP is free and battle-tested at Baidu. Commercial tools offer better support and dashboards but cost significantly more.

Block vs Monitor Mode

Start in monitor mode to see what would be blocked. Move to blocking only after you trust the tool does not break legitimate requests. All major RASP tools support this workflow.

Frequently Asked Questions

What is RASP?

RASP (Runtime Application Self-Protection) is a security technology that runs inside an application to detect and block attacks in real-time. Unlike WAFs that inspect traffic externally, RASP agents see how the application processes each request and can make more accurate blocking decisions.

How is RASP different from a WAF?

WAFs sit in front of the application and inspect HTTP traffic patterns. RASP runs inside the application and sees actual code execution. This means RASP has far fewer false positives because it knows whether a suspicious input will actually trigger a vulnerability.

Does RASP cause performance overhead?

Yes, RASP agents add some latency since they intercept function calls within the application. Typical overhead ranges from 2-10% depending on the tool and configuration. Most production deployments accept this tradeoff for the improved protection accuracy.

Which languages do RASP tools support?

RASP support varies by tool. Java and .NET have the broadest coverage. Node.js and Python support is common but less mature. Go and Rust have limited RASP options due to their compiled nature. Check each tool’s documentation for current language support.

Is there a free RASP tool?

Yes. OpenRASP is an open-source RASP tool maintained by Baidu. It supports Java and PHP, and has been used in production at scale. It is the only mature free option currently available.

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RASP covers one aspect of application security. Browse other categories in our complete tools directory.

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Written by

Suphi Cankurt

Suphi Cankurt is an application security enthusiast based in Helsinki, Finland. He reviews and compares 129 AppSec tools across 10 categories on AppSec Santa. Learn more.