What is an API DDoS attack?
An API Distributed Denial of Service (DDoS) attack is when a DDoS attack is used to target an API. The aim of an API DDoS attack is to overwhelm the API with a flood of malicious traffic or requests, making it slow, unavailable, or unable to serve legitimate users.
Unlike traditional network-based DDoS attacks that target bandwidth, API DDoS attacks often focus on exhausting application resources by sending large volumes of seemingly legitimate requests to API endpoints.
For businesses that rely on online functionality, API DDoS attacks can disrupt critical functions like logins, checkout, payment processing, inventory lookups, and order management, directly impacting revenue and customer experience.
Are APIs a common target for DDoS attacks?
Yes. Modern applications are increasingly API-driven. Mobile apps, websites, third-party integrations, AI services, and partner ecosystems all rely on APIs to exchange data. Because APIs expose valuable business functionality and are often publicly accessible, they provide an attractive target for attackers seeking to disrupt operations.
How are API DDoS attacks different from traditional DDoS attacks?
Traditional DDoS attacks primarily aim to saturate network bandwidth with massive traffic volumes. API DDoS attacks often use lower traffic volumes but target expensive application functions or backend resources.
API attacks include:
Flooding authentication endpoints with login requests
Repeatedly querying search or product catalog APIs
Overloading payment or checkout APIs
Sending high volumes of API requests that appear legitimate
Exploiting inefficient API queries to consume compute resources
These application-layer attacks can be difficult to detect because they often resemble normal user behavior.
What are the most common API DDoS attack techniques?
Attackers commonly use the following DDoS attack strategies:
HTTP GET and POST floods
API endpoint flooding
Authentication request floods
Slow HTTP attacks
Bot-driven request floods
Resource exhaustion attacks
GraphQL query abuse
Business logic abuse
Many attacks combine automation, botnets, and compromised devices to generate traffic from thousands of distributed sources.
What are the signs that an API is under a DDoS attack?
There are several key signs to look out for to help catch a DDoS attack before it is successful.
Sudden spikes in API traffic
Increased response times or latency
Higher error rates (5xx responses)
Authentication failures
Increased infrastructure costs
CPU or memory exhaustion
Database connection saturation
Service outages
Large increases in requests from a small number of endpoints or clients
Continuous monitoring, real-time analytics - and of course a dedicated DDoS mitigation solution - can help identify these anomalies before they become full-scale outages.
Best Providers for API DDoS Protection
Provider | Network DDoS (L3/4) | API / L7 DDoS | Behavioral Detection | API Rate Limiting | Bot / Automation Defense | Key API DDoS Strength |
Fastly | Edge-based DDoS mitigation designed to absorb attacks before they impact applications and origins | Strong L7 protection for APIs and web applications with enforcement at Fastly’s edge | Traffic and application signals can be used to identify anomalous and abusive request patterns | Edge rate limiting can protect specific API endpoints and constrain abusive clients | Advanced bot and abuse controls complement WAF and DDoS defenses | Programmable edge protection with rapid enforcement and granular controls close to incoming API traffic |
Akamai | Large-scale always-on/on-demand DDoS mitigation through Prolexic and Akamai’s distributed infrastructure | Strong protection against HTTP floods, API endpoint attacks and application-layer resource exhaustion | Behavioral and traffic analytics help identify anomalies and distinguish attacks from normal API activity | Granular controls for managing request rates and abusive API clients | Advanced bot management, credential-abuse and automation detection | Broad DDoS + WAAP stack combining network mitigation, API protection, WAF and bot defense |
Cloudflare | Anycast-based DDoS mitigation across its global network with automatic network-layer protection | Edge mitigation of HTTP/API floods before requests reach the origin | Uses traffic signals and adaptive detection across its network to identify anomalous traffic | Flexible rate-limiting rules based on endpoints, request characteristics and traffic patterns | Integrated bot management and automated-traffic detection | Highly integrated edge platform combining DDoS, WAF, API controls, rate limiting and bot management |
F5 | Network DDoS capabilities suited to enterprise and hybrid application environments | Application and API protection can mitigate HTTP floods and resource-exhaustion attacks | Strong behavioral and application-layer analysis, particularly when combined with F5 security products | Policy-driven controls can restrict abusive traffic and protect sensitive endpoints | Extensive bot-defense capabilities for sophisticated automated attacks | Strong enterprise application-security stack, particularly for organizations with hybrid architectures or existing F5 deployments |
Imperva / Thales | Cloud DDoS mitigation for network and infrastructure attacks | WAAP capabilities protect APIs against application-layer floods and abusive request patterns | Uses application and traffic analysis to identify suspicious activity | Rate controls can be applied to APIs and application resources | Mature bot management for distinguishing automated abuse from legitimate users | Integrated WAAP approach combining DDoS mitigation, WAF, API security and bot protection |
Radware | DDoS-specialist platform with automated mitigation of volumetric and protocol attacks | Strong application-layer DDoS capabilities targeting HTTP and API services | Behavioral algorithms establish normal traffic patterns and identify deviations associated with attacks | Rate and traffic controls help constrain abusive clients and attack patterns | Bot management helps identify malicious automation and distributed bot activity | DDoS specialization and behavioral detection, particularly for complex or rapidly changing attacks |
What should organizations look for in an API DDoS protection solution?
Organizations should look for the following capabilities in an API DDoS protection solution:
API-aware protection: A solution that understands API traffic, endpoints, methods, and usage patterns, not just IP addresses and request volumes, in order to identify attacks that traditional network DDoS defenses may miss.
L3–L7 DDoS coverage: Protects against both large volumetric attacks and application-layer attacks designed to exhaust API, application, or backend resources.
Behavioral detection: Establishes normal API behavior and detects anomalies, helping identify distributed, low-and-slow, and other attacks that may stay below static thresholds.
Granular, adaptive rate limiting: Applies controls at the endpoint, client, or request level and dynamically responds to changing attack conditions without unnecessarily throttling legitimate users.
Bot and client identification: Distinguishes legitimate API consumers from malicious bots, automated tools, and distributed attack infrastructure.
Resource-exhaustion protection: Identifies attacks targeting computationally expensive endpoints (authentication, search, GraphQL, or AI APIs) where relatively low request volumes can have significant impact.
Rapid, automated mitigation: Detects and mitigates attacks in real time with minimal manual intervention, reducing the time attackers have to affect availability.
Origin protection: Stops malicious traffic at the edge before it consumes application, compute, bandwidth, or other origin resources.
Low false-positive rates: Maintains availability for legitimate API consumers during mitigation, especially during legitimate traffic spikes that can resemble DDoS activity.
Visibility and analytics: Provides clear insight into attack sources, targeted endpoints, mitigation actions, and traffic behavior so security teams can investigate incidents and improve policies over time.
A unified platform that combines API security, DDoS protection, WAF, and bot management can simplify operations, reduce complexity, and provide more effective protection than deploying separate point solutions.
Protect your business with Fastly DDoS protection
As attackers increasingly exploit vulnerabilities in Layer 7 business logic, you must employ an array of adaptive defense strategies. No single solution provides comprehensive protection, but combining proactive and reactive mitigation techniques at the edge can effectively counter application attacks before they overwhelm infrastructure. Intelligent capabilities like machine learning and behavior analysis are beneficial for keeping up with the growing sophistication of malicious botnets and stressor services.
Fastly's DDoS Protection services provide a powerful yet flexible approach for shielding your web properties and APIs. Backed by a global edge network, the solution offers deep visibility into traffic combined with rapid threat detection and mitigation capabilities. Here's how the platform helps your business stay ahead of these threats:
Automatic mitigation of attacks: Fastly uses proactive techniques to automatically identify and neutralize DDoS attacks without requiring manual intervention. Threats are addressed immediately, minimizing disruption.
Improved resilience: With Fastly’s solution, applications, and APIs maintain consistent performance and availability, even during high-volume attacks. This resilience ensures a swift customer experience for legitimate traffic.
Dynamic detection and adaptive identification: Fastly continuously monitors incoming traffic, using advanced analytics to detect anomalous attack patterns instantaneously. Adaptive identification ensures the solution stays effective against evolving threats.
Zero attack fees: Fastly doesn't charge for attack traffic, unlike many providers. You only pay for legitimate requests, keeping operational costs predictable and reducing financial strain during prolonged attacks.
Integrated next-gen WAF: Fastly's next-gen WAF complements DDoS protection by identifying and blocking malicious web requests.
Near instant mitigation: The platform reduces the impact of attacks on end users by mitigating threats in seconds.
Versatile deployment: Fastly protects applications of all sizes with fast, upgradable defenses.
Learn how Fastly can protect your applications, APIs, and microservices, ensuring your business stays secure and resilient to developing threats.