SafeLine

Open source alternative to Cloudflare WAF, Imperva Cloud WAF, AWS WAF, F5 BIG-IP Advanced WAF and Akamai App and API Protector

23.1K stars
GPL-3.0
Active this week
Last commit 6 days ago

Last verified Oct 29, 2026

Secure web apps with a self-hosted WAF using semantic analysis to block SQL injection, XSS, DDoS, and bot attacks with near-zero false positives.

Visit website GitHub23.1K Deploy on Hostinger

Read the full breakdownWho it is for, how it works, trade-offs and the FAQ

who it's for

Who SafeLine is for#

DevOps teams self-hosting web apps on a VPS or cloud VM

SafeLine installs as a reverse proxy in front of all hosted applications, providing SQL injection, XSS, bot filtering, and rate limiting without per-request billing. A single deployment covers multiple applications without changing their individual configurations.

Skip if:

Skip if you use a managed cloud service that already includes WAF functionality at your tier (such as AWS ALB with WAF integration already configured) and the cost is within budget.

Teams with data sovereignty or compliance requirements

All traffic stays on your own infrastructure. SafeLine never routes requests through a third-party service, which matters for healthcare, financial, or government applications operating under compliance frameworks that restrict external traffic routing.

Skip if:

Skip if your threat model permits third-party traffic processing and a managed WAF like Cloudflare WAF is already within your compliance envelope with simpler operational overhead.

Developers protecting staging environments and internal tools

SafeLine's authentication challenge lets you password-gate any web application without modifying its code. Staging environments, admin panels, and internal dashboards that run on public IPs can be locked down at the WAF layer with a single configuration entry.

Skip if:

Skip if your staging environment is already behind a VPN or private network. Network-level access control is simpler than a WAF for this specific use case.

API teams protecting endpoints from scraping and rate abuse

Rate limiting and bot challenge capabilities apply to API endpoints. The Kong Gateway plugin integrates SafeLine into existing Kong-managed API infrastructure, adding abuse protection and rate limiting without changing endpoint logic or application code.

Skip if:

Skip if your API gateway already handles rate limiting and bot protection within its native feature set. Adding another proxy hop adds latency and operational surface area without incremental benefit.

the problem

The problem it solves#

Running web applications without a WAF layer exposes you to SQL injection, XSS, brute-force login attacks, and bot traffic that your application code was never designed to handle. The common paths forward both carry real pain: commercial WAF services like Cloudflare WAF Pro and AWS WAF charge per request and per rule, and they route all your traffic through their own infrastructure, which creates data sovereignty concerns for regulated industries.

ModSecurity, the most common open source alternative, requires manual rule writing and produces false positive rates above 17% at aggressive detection settings. That means either blocking legitimate users or lowering protection. Teams without dedicated security engineering often end up with no WAF layer at all, leaving their applications exposed to attacks they were hoping to avoid.

how SafeLine solves it

How it solves it#

Semantic Attack Detection

SafeLine uses semantic analysis to detect SQL injection, XSS, code injection, OS command injection, CRLF injection, XXE, SSRF, path traversal, and backdoor attacks. Semantic analysis evaluates the intent of HTTP traffic rather than matching static patterns, which is how SafeLine achieves a 0.07% false positive rate at 71.65% attack detection in benchmark tests across 33,669 samples.

Rate Limiting and DoS Defense

Throttles traffic that exceeds defined limits to defend against HTTP flood attacks, brute-force attempts, and traffic surges. Rate limiting is configured per endpoint and applied at the reverse proxy layer before the request reaches your application, keeping your web server resources available to legitimate users under high-volume attack conditions.

Anti-Bot Challenge

Presents a challenge to traffic that appears automated. Human users proceed normally; crawlers and bots are blocked. The challenge fires at the WAF layer before the request reaches your application, so bot traffic does not consume backend resources or pollute your server logs with automated requests disguised as legitimate visits.

Authentication Challenge

Password-gates any web application with a single configuration step. Visitors must enter the correct password to proceed; all other traffic is blocked at the WAF layer. Useful for protecting staging environments, admin panels, or internal tools that run on public IPs but should not be accessible to the open internet.

Dynamic HTML and JavaScript Encryption

When dynamic protection is enabled, SafeLine re-encrypts the HTML and JavaScript in each response before it leaves the server. The content a browser renders differs from what automated scanners read, making it harder to reverse-engineer application structure or identify attack surfaces by inspecting the source.

strengths · trade-offs

Strengths and trade-offs#

Strengths

Near-zero false positives at high detection ratesIn benchmark testing across 33,669 samples, SafeLine's balance mode achieved 71.65% attack detection with a 0.07% false positive rate and 99.45% overall accuracy. ModSecurity at Level 1 reaches 69.74% detection but produces a 17.58% false positive rate. The semantic analysis approach closes the gap between catching attacks and blocking legitimate traffic that rule-based WAFs have historically struggled with.
Proven at production scaleAccording to the project, SafeLine runs on over 700,000 servers protecting more than 2,000,000 websites and handling more than 50,000,000,000 HTTP requests per day. The repository had its last commit in October 2026 and has 23,074 GitHub stars, indicating active maintenance and real production adoption rather than a project with high stars and low use.
GPL-3.0 with no per-request billingThe community edition is GPL-3.0 licensed. You run it on your own servers and pay nothing per request, regardless of traffic volume. Compared to Cloudflare WAF Pro or AWS WAF, there is no per-million-request cost to model at scale, and no billing events when traffic spikes during an attack.
Kubernetes and API gateway integrationAn Ingress-NGINX plugin integrates SafeLine filtering into Kubernetes ingress traffic. A Kong Gateway plugin covers APIs managed behind a Kong gateway. Both integrations let existing infrastructure adopt SafeLine filtering without changing application deployment configurations.

Trade-offs

-Open-core: advanced features require paid PRO editionSafeLine follows an open-core model. The community edition covers the core WAF capabilities under GPL-3.0, but the PRO edition adds features not available in the open tier. Teams that need those additional capabilities must evaluate commercial pricing, which changes the cost calculus for organizations comparing SafeLine to purely open source options.
-Reverse proxy hop adds latency to every requestSafeLine sits between clients and every application it protects, adding a network processing step to each request. Published documentation does not include latency benchmarks or performance data under load. Teams with strict latency requirements should run their own performance tests before committing SafeLine to the request path in front of time-sensitive applications.
-GPL-3.0 restricts redistribution as a managed serviceRunning SafeLine on your own infrastructure for your own applications, including commercial internal use, is fully permitted under GPL-3.0. If you want to offer SafeLine as a managed WAF service to external customers, GPL-3.0 requires you to distribute any source modifications and may not permit that use case without a separate commercial license from the maintainers.

versus alternatives

SafeLine vs alternatives#

SafeLine vs Cloudflare WAF

Both protect web applications from SQL injection, XSS, and bot attacks, but they operate on different deployment models. Cloudflare WAF routes all web traffic through Cloudflare's global edge network; SafeLine runs as a reverse proxy on your own server. The benchmark data in the SafeLine project covers Cloudflare's free tier specifically.

Feature	SafeLine	Cloudflare WAF
License	GPL-3.0 (community)	Proprietary
Self-hosting	Yes	No
Traffic routing	Stays on your servers	Routes through Cloudflare edge
Pricing	Free (community edition)	Free tier available; paid tiers for advanced rules
Detection rate (benchmark)	71.65% balance / 76.17% strict	10.70% (free tier)
False positive rate	0.07%	0.07%

SafeLine is the better choice when data sovereignty matters, when you cannot route traffic through a third party for compliance reasons, or when per-request billing is a concern at scale. The benchmark detection comparison is against Cloudflare's free tier; paid tiers use more comprehensive rule sets. Cloudflare WAF is worth choosing when you need edge-network DDoS mitigation that absorbs attacks before reaching your origin, or when a DNS-based setup with no infrastructure to manage is the priority.

SafeLine vs AWS WAF

AWS WAF integrates natively into AWS load balancers and CloudFront distributions. SafeLine works on any HTTP server regardless of hosting provider, making it the more infrastructure-agnostic option.

Feature	SafeLine	AWS WAF
License	GPL-3.0 (community)	Proprietary
Self-hosting	Yes	No (AWS-managed)
Infrastructure dependency	None	Requires ALB, CloudFront, or API Gateway
Pricing	Free (community)	Usage-based per WebACL and per million requests
Attack detection method	Semantic analysis	Managed or custom rule sets

SafeLine is the right fit for teams not on AWS or using mixed hosting providers, and for situations where traffic volume makes usage-based billing expensive. AWS WAF is the better option when your application already runs behind an AWS Application Load Balancer or CloudFront distribution and you want WAF protection without adding a separate reverse proxy to your request path.

tech stack · detected from GitHub

What it's built on#

Languages: C++GoLuaPython

frequently asked

FAQ#

Is SafeLine free to use?

The community edition is GPL-3.0 licensed and free to run on your own infrastructure, including for commercial team use. There is no per-request billing or seat licensing for the self-hosted community edition. A paid PRO edition is available for teams that need features beyond what the community tier provides.

How does SafeLine compare to Cloudflare WAF?

SafeLine self-hosted keeps all traffic on your infrastructure; Cloudflare WAF routes traffic through Cloudflare's edge network, which some compliance frameworks restrict. SafeLine's community edition has no per-request billing, while Cloudflare WAF charges per rule and per million requests at paid tiers. Cloudflare WAF is the better fit when you need edge-network DDoS absorption before traffic reaches your origin, or when you want no infrastructure to manage.

Can SafeLine protect multiple web applications from one installation?

Yes. A single SafeLine installation acts as a reverse proxy for multiple web applications. Each application is registered in the SafeLine management interface, and filtered traffic is routed to each one independently. There is no per-application licensing fee in the community edition.

What types of attacks does SafeLine block?

SafeLine blocks SQL injection, XSS, code injection, OS command injection, CRLF injection, LDAP injection, XPath injection, RCE, XXE, SSRF, path traversal, and backdoor attempts. It also handles HTTP flood attacks, brute force, and bot traffic. The semantic analysis engine evaluates attack intent rather than matching static rule signatures, which reduces false positives compared to rule-based systems.

Is SafeLine production-ready?

Yes. The project reports over 700,000 server installations protecting more than 2,000,000 websites and handling more than 50,000,000,000 HTTP requests per day. The repository has been actively maintained with commits through October 2026 and has over 23,000 GitHub stars. It is listed in the awesome-selfhosted directory and has been recognized by cybersecurity publications.

also worth a look

Similar open-source tools#

Minimal

Alternative toChainguard Images

150 hardened container images, MIT-licensed, signed and rebuilt daily

554 GitHub stars
Licence MIT

Docker Mailserver

Alternative toGoogle Workspace

Postfix/Dovecot mail server in Docker, configured with plain files.

19,686 GitHub stars
Licence MIT

Radar

Alternative toLens

Open-source Kubernetes UI with topology, GitOps, and AI agent MCP.

3,908 GitHub stars
Licence Apache-2.0

Statlite

InSecurity & Monitoring

Self-hosted Spring Boot monitoring, no Prometheus or Grafana needed

188 GitHub stars
Licence MIT

Oxynote

Alternative toNotion

Technical wiki with live metrics, draft reviews, and real-time editing

392 GitHub stars
Licence Apache-2.0

Homeio

Alternative toUnraid

Browser desktop for your self-hosted home server

94 GitHub stars
Licence AGPL-3.0

by category

Open source tools in these categories#

143

Security & Monitoring

REA (Reverse Engineer Anything), RustDesk, Uptime Kuma 95

DevOps & CI/CD

Nvm, Uptime Kuma, Netdata

Hostinger

Self-host SafeLine on a Hostinger VPS

Keep it running 24/7, even when your laptop is off. A Hostinger VPS gives it a server of its own.

01
Choose a plan
Starts from $6.49/mo
02
Apply
Extra 10% off yearly plans
03
Install SafeLine
On a server that stays on
04
Start building
Focus on the app, not the server

Deploy on Hostinger

Inbox Zero

Alternative toSuperhuman

AI email assistant that drafts replies and clears your inbox

12,826 GitHub stars
Licence AGPL-3.0
#Email

Omnara

Alternative toClaude Managed Agents

Open-source agent deployment API. Self-host or use Omnara Cloud.

3,296 GitHub stars
Licence Apache-2.0
#AI Agents

rakazo

Alternative toGrok Bot

AI teammates you own: your keys, your model, your machine.

5,914 GitHub stars
Licence Apache-2.0
#AI Agents

Advertise your product

The projects we add and every new guide. Free, unsubscribe any time.

Find open source alternatives to paid software

SafeLine vs Cloudflare WAF

Feature	SafeLine	Cloudflare WAF
License	GPL-3.0 (community)	Proprietary
Self-hosting	Yes	No
Traffic routing	Stays on your servers	Routes through Cloudflare edge
Pricing	Free (community edition)	Free tier available; paid tiers for advanced rules
Detection rate (benchmark)	71.65% balance / 76.17% strict	10.70% (free tier)
False positive rate	0.07%	0.07%

SafeLine vs AWS WAF

AWS WAF integrates natively into AWS load balancers and CloudFront distributions. SafeLine works on any HTTP server regardless of hosting provider, making it the more infrastructure-agnostic option.

Feature	SafeLine	AWS WAF
License	GPL-3.0 (community)	Proprietary
Self-hosting	Yes	No (AWS-managed)
Infrastructure dependency	None	Requires ALB, CloudFront, or API Gateway
Pricing	Free (community)	Usage-based per WebACL and per million requests
Attack detection method	Semantic analysis	Managed or custom rule sets