Why Arcis

Five honest comparison pages against the closest tools in this space. Arcis is not the right answer for every problem; these pages tell you when it is and when it isn't.

Where Arcis is structurally different

• Three SDKs at parity. Node + Python + Go from a single specification with shared test vectors. Arcjet is Node-primary with Python as a sidecar. Aikido Zen is Node-primary; Python is Django/Flask only. Snyk has no runtime SDK.
• Zero account, zero phone-home. npm install @arcis/node && app.use(arcis()) works fully offline. Arcjet and Aikido gate detection mode behind tokens; Snyk's CLI requires snyk auth.
• Runtime defense + supply chain + audit + REPL in one tool. Aikido has runtime + SAST + SCA as separate products. Snyk has Code + OS but no runtime defender. Arcjet has runtime but no SCA, no audit CLI, no REPL.
• Curated threat-DB transparency. The 100-entry SCA database is auditable in the repo. Aikido's threat DB is closed; Snyk's is closed; Arcjet's bot list is closed.
• MIT license, end to end. No freemium gates on detection rules. No "Pro" features hidden behind a paywall in the SDK.
• Inside-the-app, not outside. Sees parsed JSON, sanitized session state, and decoded headers. WAFs and CAPTCHAs cannot.

Detailed comparisons

Direct runtime competitors

• vs Arcjet — closest competitor. Cloud-decisioned vs in-process; Node-primary vs three SDKs at parity; paid SaaS vs MIT-licensed open source.
• vs Aikido Zen — RASP via monkey-patching dangerous sinks. Aikido covers what it knows about; Arcis covers the request boundary. Token-required vs zero-config.

Supply chain + SAST

• vs Snyk — the SCA + Code leader. Snyk goes broader (containers, IaC); Arcis is a developer-installed library with built-in runtime defense Snyk doesn't have. Per-developer pricing vs open source.

Edge defenders

• vs Cloudflare WAF — complementary, not competitive. WAF stops volumetric attacks before origin; Arcis stops payload-level attacks after parsing. Use both.
• vs CAPTCHAs — same goal (block bots), different cost model. CAPTCHAs add friction to every visitor; Arcis bot detection runs invisibly.

When Arcis is not the right answer

Honest take. Use a different tool when:

• You need volumetric DDoS defense. Use Cloudflare, Akamai, or your CDN. Arcis is a per-request library; it cannot drop traffic before it reaches your origin.
• You need a managed SaaS with a sales team. Use Arcjet or Snyk. Arcis ships as a library; we will not sell you an "enterprise contract."
• You need a deep container / IaC scanner. Use Snyk or Trivy. Arcis only covers code and dependency lockfiles.
• You need cloud-trained ML bot scoring. Use Cloudflare Bot Management or Arcjet. Arcis bot detection is signature + behavioral, not ML.
• You need HIPAA / SOC2 audit reports for the security tool itself. Arcis is MIT-licensed open source; the audit posture is the code you can read. Tools that sell to regulated industries have compliance reports we don't.

When Arcis is the right answer

• You want runtime defense that lives in-process, not in your edge or a sidecar.
• You ship Node + Python + Go and want the same security contract across all three.
• You want to start with zero account, zero phone-home, fully offline.
• You want one CLI that covers SAST + SCA + endpoint probing, with an interactive console on top.
• You want to audit every detection rule and every threat-DB entry in source.
• You value lean dependency footprint and want a library, not a platform.