SafeLine
SafeLine is a self-hosted Web Application Firewall (WAF) and reverse proxy written in Go that blocks common web attacks like SQL injection, XSS, and bot abuse. It can be deployed in front of web applications to filter malicious traffic and includes rate limiting, CAPTCHA challenges, and HTML/JS encryption features.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | chaitin/SafeLine |
| Owner | chaitin |
| Primary language | Go |
| License | GPL-3.0 — OSI-approved |
| Stars | 21.7k |
| Forks | 1.4k |
| Open issues | 93 |
| Latest release | v9.3.9 (2026-06-17) |
| Last updated | 2026-06-17 |
| Source | https://github.com/chaitin/SafeLine |
What SafeLine is
SafeLine operates as a reverse proxy that inspects HTTP/HTTPS traffic before it reaches backend applications, using rule-based detection to identify and block malicious payloads. It is written in Go, supports IP-based rate limiting, dynamic code encryption, and anti-bot challenges; deployment typically involves Docker or direct binary installation.
Get the SafeLine source
Clone the repository and explore it locally.
git clone https://github.com/chaitin/SafeLine.gitcd SafeLine# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Reverse proxy deployment model requires network topology redesign; ensure backend application endpoints are not directly accessible post-SafeLine installation.
- Rule tuning and false-positive management are critical; SafeLine reports 0.07% false positives at balance settings but effectiveness varies by application workload.
- SSL/TLS termination at SafeLine means certificate management and renewal must be integrated into deployment automation.
- Traffic logging and forensics capabilities should be integrated with SIEM; ensure disk and network capacity for high-volume request inspection.
- Rate limiting and bot detection thresholds must be calibrated per-application; default settings may block legitimate users or allow attack traffic.
When to avoid it — and what to weigh
- Need Commercial Support SLA — SafeLine is GPL-3.0 licensed; commercial support, SLAs, and indemnification are not documented. If you require vendor-backed support guarantees, consider proprietary WAF solutions.
- Require Proprietary Rule Sets or Consulting — SafeLine's threat detection relies on open-source rules. If your compliance framework mandates vendor-maintained attack signatures or deep security consulting, alternative WAF providers may fit better.
- Minimal DevOps Capacity or Self-Hosting Constraints — Self-hosted WAFs require operational overhead: patching, monitoring, log management, and rule tuning. Managed cloud WAF services may be more appropriate if staffing is limited.
- Regulated Industries with Strict Audit Requirements — Compliance audits in healthcare, finance, or government often require vendor certifications, formal change control, and documented security assessments. Open-source projects may require additional governance scaffolding.
License & commercial use
SafeLine is licensed under GPL-3.0 (GNU General Public License v3.0). GPL-3.0 is a strong copyleft license that requires any derivative works and distributed versions to be made available under the same license. The license is permissive for internal use but restricts proprietary redistribution.
GPL-3.0 permits use of SafeLine for commercial web applications (as an internal tool), but does not grant rights to create proprietary derivative works or closed-source modifications. If you modify SafeLine, those modifications must also be GPL-3.0. Requires review: commercial support, maintenance agreements, and indemnification are not documented; contact the maintainers (Chaitin) for commercial licensing clarity.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Adequate |
| License clarity | Clear |
| Deployment complexity | Moderate |
| DEV.co fit | Good |
| Assessment confidence | High |
SafeLine inspects HTTP/HTTPS traffic and applies pattern-matching rules to detect malicious payloads. Key considerations: (1) SafeLine itself becomes a critical infrastructure component; its compromise exposes all protected applications; (2) Rule effectiveness varies—reported detection is 71.65% (balance mode) to 76.17% (strict mode), meaning some attacks may bypass; (3) False positives at 0.07% are low but can block legitimate users in strict mode; (4) Encryption features (HTML/JS dynamic protection) add performance overhead and complexity; (5) No formal security audit, penetration test results, or CVE disclosure policy are documented; (6) Rely on upstream Go and dependency security; check SafeLine's GitHub Security tab for advisories. Requires review: formal threat model, secure configuration hardening guide, and incident response procedures.
Alternatives to consider
ModSecurity (Open Source)
Mature, rule-based WAF often deployed with nginx/Apache. Lower detection (69.74% vs SafeLine's 71.65%) and higher false positives (17.58%) but lighter footprint for simple rule sets. LGPL licensed.
Cloudflare WAF (Managed SaaS)
Managed, cloud-native WAF with 99.93% uptime SLA, vendor support, and low false positives (0.07%). Higher cost and vendor lock-in; suitable for teams prioritizing managed operations over self-hosting.
OWASP ModSecurity Core Rule Set (CRS) on nginx
Free, open-source WAF rules deployable on any reverse proxy. Requires manual tuning and operations expertise but offers full control and no license restrictions.
Build on SafeLine with DEV.co software developers
Our DevOps and web app teams can help you assess SafeLine's fit, configure production deployments, and integrate security monitoring. Contact us for a security architecture review.
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SafeLine FAQ
Is SafeLine suitable for production?
Can I modify SafeLine and keep it proprietary?
What attacks does SafeLine detect?
Do I need to change my application code to use SafeLine?
Software developers & web developers for hire
DEV.co helps companies turn open-source tools like SafeLine into production software. Our software development services cover the full lifecycle — architecture, web development, integration, and maintenance — delivered by software developers and web developers who ship. Engage our software development agency to implement or customize it for your open-source devops stack.
Need Help Deploying SafeLine or Evaluating WAF Options?
Our DevOps and web app teams can help you assess SafeLine's fit, configure production deployments, and integrate security monitoring. Contact us for a security architecture review.