Arcis vs Cloudflare WAF
Cloudflare WAF filters traffic at the edge, before it reaches your origin. Arcis filters traffic inside your application, with full request context. Both block attacks; they live at different layers and answer different questions.
TL;DR
An edge WAF only sees what's on the wire: headers, URL, raw body. It doesn't know which route the request hit, what the schema expected, or what your handler is about to do with the input. Arcis runs after routing and JSON parsing, so it sees the structured request and can sanitize it surgically. The two are complementary: Cloudflare WAF filters obvious garbage at line rate, Arcis catches what's left in app-aware context.
Where Cloudflare WAF wins
- Stops traffic before it costs you. An edge WAF blocks attacks at Cloudflare's network, not your origin. Bandwidth, CPU, and request budget never get touched. For DDoS-class volumes, that's the difference between staying online and going down.
- Deployed by config, not code. Turning on managed rules is a dashboard click. No deploy, no rebuild, no SDK install. For ops teams that don't own the application code, this matters.
- Threat intelligence at scale. Cloudflare sees a meaningful share of global traffic. Their managed rules update against attacks they observe across millions of sites.
Where Arcis wins
- Application context. An edge WAF sees a JSON blob; Arcis sees parsed objects with route metadata and the schema your handler expects. That extra context lets Arcis sanitize specific fields (sanitize the comment body but leave the email field alone) instead of blanket-blocking.
- Lower false-positive rate on legitimate traffic. Edge WAFs see "string contains
SELECT" and decide to block; Arcis sees thatSELECTis in a known-safe field of a search query and lets it through. App-aware filtering has fundamentally better precision. - Works without a CDN in the path. If your service runs behind a different CDN, on a private network, in a Kubernetes cluster, or in a regulated environment where Cloudflare can't see plaintext traffic, an edge WAF doesn't help. Arcis runs wherever your code runs.
- Includes vectors a WAF doesn't cover. Application-layer concerns like prompt injection, NoSQL operator filtering, mass assignment, prototype pollution, or LLM token-budget enforcement happen after parsing and routing. An edge WAF can't see them.
- No vendor lock-in or per-request cost. Arcis is MIT and runs in-process. No metered traffic, no plan tiers, no terms of service governing what you can do with your data.
Capability matrix
Comparison reflects public state of both products as of 2026-05-10.
| Capability | Cloudflare WAF | Arcis |
|---|---|---|
| Layer | Edge (network) | Application (in-process) |
| Sees structured request | No (only raw bytes) | Yes (parsed body, query, headers, route) |
| Stops traffic before origin | Yes | No (origin still receives the request) |
| DDoS volumetric defense | Yes (huge global capacity) | No (relies on edge or upstream) |
| XSS / SQLi pattern matching | Yes (Managed Rules) | Yes (per-field sanitization) |
| Bot detection | Yes (their Bot Management product) | Yes (635 patterns + behavioral) |
| Rate limiting | Yes | Yes |
| Prompt injection | No | Yes (28 signatures) |
| NoSQL operator filtering | No (can't see parsed JSON) | Yes |
| Prototype pollution defense | No | Yes |
| Per-field policy | No | Yes (sanitize body but skip query, etc.) |
| Works without CDN | No | Yes |
| License | Commercial (Plan-tiered: Pro/Business/Enterprise) | MIT, open source |
How to choose
This is a layered defense, not an either-or. Use both if you have a CDN already. Cloudflare WAF blocks the volumetric noise at line rate; Arcis catches the targeted, application-aware attacks that get through.
Pick only Cloudflare WAF if:
- You can't modify the application code (legacy stack, vendor product).
- Volumetric DDoS is your primary concern.
- You're OK with edge-layer false positives and don't need per-field precision.
Pick only Arcis if:
- You don't run behind Cloudflare (different CDN, private network, regulated environment, edge runtime).
- You need application-aware filtering: per-field policies, NoSQL operator stripping, prompt injection, mass assignment.
- You don't want vendor lock-in or per-request edge fees.
Bottom line
Cloudflare WAF and Arcis solve different problems at different layers. The honest answer: if you can run both, do. If you can only run one, the question is whether your biggest risk is volume (pick Cloudflare) or targeted application-layer abuse (pick Arcis).