A fully programmable secure web gateway

A Fully Programmable Secure Web Gateway

Cloudflare is extending its Zero Trust portfolio with a programmable Secure Web Gateway (SWG) that runs custom logic directly in the policy evaluation path. By integrating Cloudflare Workers with Gateway and Data Loss Prevention (DLP), customers can now write arbitrary code that transforms traffic, queries external data sources, or applies bespoke validation before a decision to allow, block, isolate, or log is made.

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Why Traditional Gateways Hit a Ceiling

For three decades, most SWGs have followed a simple model: match a condition, then fire a terminal action (allow, block, isolate, log). This works for common use‑cases but falls short when environments become complex—multiple SaaS apps, custom authentication flows, or nuanced data‑handling policies. Organizations are forced into one of two compromises:

1. Self‑managed firewalls/proxies – full control but high operational overhead and limited portability.
2. Vendor‑locked appliances – low maintenance but constrained to the vendor’s predefined rule set.

Cloudflare’s experience building Gateway for years shows that many customers repeatedly hit this trade‑off, seeking deeper integration without the cost of managing their own infrastructure.

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True Programmability: Workers Meet Gateway

The new Forward action and custom validation functions expose a Workers runtime inside the gateway decision engine. Key capabilities include:

• Inline traffic transformation – modify HTTP headers, rewrite URLs, or inject security tokens on the fly.
• External data lookups – call internal APIs, threat‑intel services, or identity providers during policy evaluation.
• Fine‑grained DLP checks – run custom regex or ML models against payloads before data leaves the network.
• Zero‑trust integration – all features are available across Cloudflare’s Zero Trust plans, keeping the management experience consistent.

Because Workers execute at the edge, these custom actions add minimal latency while preserving the global scale and reliability Cloudflare is known for.

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Practical Use Cases

| Scenario | How a Worker‑Powered Gateway Helps | |----------|--------------------------------------| | Dynamic SaaS access | Query a corporate directory to verify a user’s role before allowing API calls to a third‑party service. | | Context‑aware content filtering | Inspect request payloads for PII patterns and redact or block them based on regional compliance rules. | | Adaptive threat response | Pull real‑time threat scores from an internal SIEM and adjust block thresholds on a per‑request basis. | | Custom authentication flows | Generate one‑time tokens or perform OIDC token introspection before forwarding traffic to legacy applications. |

These examples illustrate how security teams can embed organization‑specific logic without deploying separate proxies or rewriting large rule sets.

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Getting Started

1. Enable the Forward action in the Cloudflare Dashboard under Gateway → Policies.
2. Create a Worker using the familiar JavaScript/TypeScript API. The runtime provides request and response objects, plus helper methods to read DLP metadata.
3. Attach the Worker to a policy as a custom validation function. The function returns a boolean (allow/deny) or a transformed request object.
4. Test in staging using the built‑in request preview tool, then roll out to production.

Documentation includes sample Workers for common patterns—header injection, external risk lookups, and payload sanitization—so teams can iterate quickly.

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The Bottom Line

By marrying the flexibility of Cloudflare Workers with the security posture of Gateway and DLP, Cloudflare delivers a truly programmable SWG that eliminates the classic security trade‑off. Teams gain the ability to tailor policies to their unique environments while offloading the heavy lifting of scaling, patching, and availability to Cloudflare’s edge network. The result is a more adaptable, lower‑maintenance security layer that can evolve alongside modern, distributed workloads.