Aikido Zen Firewall vs Arcjet

Arcjet is an alternative to Aikido Zen Firewall for protecting your applications from bots, implementing rate limiting, and defending against other attacks. Both products offer security features, but there are some key differences to consider when choosing between them.

Key differences: Aikido vs Arcjet

Security components for developers: Arcjet provides a range of security components that developers can integrate directly into their applications, including bot management, rate limiting, email verification, personal information detection & redaction, and a full web application firewall (WAF) that covers SQL injection, cross-site scripting, file inclusion attacks, and others. Aikido’s Zen Firewall focuses on runtime application protection: blocking dangerous user input (injection, path traversal, SSRF, etc.), per-route and per-user rate limiting, and blocking bots, Tor traffic, known threat actors, and traffic by country. Aikido also offers a broader cloud security platform (code scanning, cloud scanning, etc.) that is not directly comparable to Arcjet’s SDK.
Integration: Arcjet is designed to integrate as a library directly into your codebase. You define rules in code and call Arcjet alongside your application logic, and it does not modify your runtime or frameworks. Arcjet works with any modern JS/TS framework or bundler, and rules can be adjusted dynamically at runtime as regular code. Aikido’s Zen Firewall only works with Node.js and monkey-patches your code at runtime to insert security checks, which can lead to unexpected behavior, latency issues, and makes debugging more difficult. Configuration for Aikido is handled primarily through environment variables and the Aikido dashboard rather than rules-as-code inside your application.
Framework, runtime & language support: Arcjet currently focuses on the JavaScript and TypeScript ecosystem, with native ESM-only SDKs for platforms like Next.js, Node.js, Bun, Remix, SvelteKit, NestJS, and others. Aikido’s Zen Firewall has a wider language surface area, with agents for Node.js, Python, PHP, Java, .NET, and Ruby. However, Aikido’s monkey-patching approach causes issues with certain fameworks, such as not being able to use custom rate limits by user ID in Next.js, problems with bundlers](https://github.com/AikidoSec/firewall-node/blob/2f39052390e6ceff845a8f3addfefe7237b42f8d/docs/bundler.md) and Aikido’s experimental ESM support requires you to start your node process with a wrapper).
Real time analysis: Aikido uses a “local-only” approach to analyzing requests, meaning all decisions are made based on data available locally. Aikido handles bot detection through user agent analysis, with optional configuration for blocking specific IPs or countries and periodic refreshes of threat data. Arcjet takes a “local-first” approach where analysis is attempted first locally and if a high confidence decision can’t be made, combines the local analysis with cloud-based intelligence to provide more accurate and up-to-date threat detection. Arcjet’s cloud component allows it to leverage global threat data, IP reputation data, machine learning models, and other advanced techniques whilst still keeping sensitive data local. As a result, Arcjet can provide more effective protection against new threats with rule updates as they emerge.

Comparison

Area	Arcjet	Aikido (Zen Firewall)
Product scope	In-code security SDK for JS/TS apps: bot protection, rate limiting, WAF (Shield), email validation, signup protection, sensitive info detection & redaction, filters.	Firewall focused on Node.js for JavaScript, with agents for other languages.
Languages & platforms	JS/TS only today. SDKs for Astro, Bun, Deno, Fastify, NestJS, Next.js, Node.js, Nuxt, React Router, Remix, SvelteKit, etc.	Multiple languages: Python, PHP, Java, each with its own agent and framework support matrix. In the JS ecosystem Aikido only supports Node.js.
Integration model	Library you import and call from your handlers or middleware. Rules are written in code and can branch on any request context (user ID, plan, route, feature flags, etc.).	Agent embeds into the runtime by monkey-patching frameworks, built-ins and libraries automatically; most behavior and policies are configured via dashboard and environment variables, not per-handler code.
Runtime & module system	ESM-only. Designed for modern runtimes and edge environments.	Node.js agent currently CommonJS-only; ESM is documented as experimental/limited and may require wrappers or special setup.
Bot protection	Rules defined in code with rich request context (user, headers, IP, path, plan, etc.); can be combined with rate limits and other rules in a single decision.	Maintained list of bot user agent signatures plus IP-based controls (bots, known threat actors, Tor) and geo-blocking, driven from the Aikido dashboard.
Rate limiting	Rules-as-code: define per-route, per-user, per-account, or arbitrary key function; backed by Arcjet Cloud API with local caching for low latency.	Route and user-centric rate limiting configured primarily via the dashboard; supports user-aware rate limiting with limitations with some frameworks e.g. Next.js, but not a general-purpose rate limiting API inside your code.
WAF / attack coverage	Shield WAF integrated into the SDK to detect and block common web attacks (SQLi, XSS, file inclusion, etc.).	Performs in-process taint-style analysis by instrumenting code paths to detect injections, path traversal, SSRF and other common attack patterns.
Data & privacy model	”Local-first”: a WebAssembly engine runs inside your app; decisions are taken locally where possible and reported asynchronously. Some rules (rate limiting, Shield) call the Cloud API with request metadata, not full payloads, and results are cached.	”Local-only” for security checks: decisions are made inside your process. Metadata about attacks and events is reported back for dashboards and analytics.
Configuration	Everything is code: rules, thresholds and behavior live alongside your application logic; works naturally with env-specific configs, feature flags, and tests.	Core behavior configured in the Aikido UI (routes, rate limits, bot/IP rules, countries) plus environment variables; less emphasis on rules-as-code and per-route custom logic in the app itself.
Hosting / vendor lock-in	Platform-agnostic. Works wherever you can run your JS/TS app (Vercel, Netlify, Fly.io, Render, Kubernetes, self-hosted, etc.).	Also platform-agnostic, but tied to Aikido’s broader appsec platform. Some limitations for certain frameworks e.g. Next.js only supported in standalone mode (inside a Docker container).
Local development	Same behavior as production; you call the SDK in dev and can inspect decisions directly, including detailed reasons and metadata.	Installed like a tracing/profiling agent; runs locally with the same instrumentation model as production, with events visible in the Aikido dashboard once connected.

When to choose which

If you’re building a modern application JS/TS and care about predictable behavior, testability, and treating security as code, Arcjet is usually the better default. If you need a multi-language runtime firewall tightly coupled to Aikido’s broader security platform, Zen Firewall can be the right fit.

Choose Arcjet if…

Your core stack is JS/TS You live in Next.js, Node, Bun, Remix, SvelteKit, etc. You want an ESM-first SDK that behaves like any other library, works on edge runtimes, and doesn’t depend on runtime patching or agents.
You want security as part of your application design You’re happy to write rules in code, in the same place as your auth, billing, and routing logic. You want to express “block this bot”, “rate limit per account”, or “reject signups with disposable emails” as normal functions and ship them via your usual code review and CI.
You care about strong primitives beyond “firewall” Bot protection, rate limiting, WAF, email verification, signup protection, and PII detection/redaction are all part of the Arcjet product suite. You’d rather compose these into flows than sprinkle generic “block this request” calls around.
You want hybrid local + cloud analysis, not just IP lists You like the idea of a local WebAssembly engine plus cloud-side context (global reputation, richer analysis) with clear, explicit calls from your code — not a black-box agent making decisions you can’t easily trace.

In short: if your product is primarily JS/TS and you want security that feels like part of your application architecture, Arcjet is the better, developer-first choice.

Choose Aikido if…

You have a genuine polyglot estate You’re running Node, Python, PHP, Java, .NET, Ruby, etc., and you want one vendor with agents for all of them, integrated into a broader platform that also does code, cloud and container scanning.
You want agent-style runtime protection with minimal code changes You’re comfortable installing agents that instrument frameworks, built-ins and libraries, and you prefer to drive most policy from a dashboard and environment variables rather than writing rules in code.
You’re already bought into Aikido’s platform You want Zen as another module in the same place you manage SAST, cloud scanning and other security controls, and are happy with CommoJS-only Node.js-only monkey-patching.

Aikido makes more sense when the primary constraint is “one security vendor and agent model across many languages” and you’re happy to accept that operational shape.

FAQ

Can I use Arcjet and Aikido at the same time?

Yes. Arcjet runs as a normal library inside your JS/TS code, while Aikido Zen runs as an agent that injects into your runtime. You can start by adding Arcjet for things that are easier as rules-as-code (bot protection, signup protection, rate limiting) while keeping Aikido for other languages or existing policies. Over time you can migrate traffic and rules to Arcjet route by route.

What if I have services in Python, PHP, Java, .NET or Ruby?

Arcjet is currently focused on JavaScript and TypeScript. If a large part of your stack is non-JS, you have a couple of options:

Use Arcjet for the JS/TS functions and user-facing APIs where latency and developer ergonomics matter most.
Keep Aikido on other languages, or use their platform where you don’t want to touch application code.

If your primary product surface is JS/TS, you’ll usually get a better developer experience by standardizing on Arcjet there and treating other languages as exceptions.

Which should I choose for a greenfield JS/TS SaaS?

If the app is primarily JS/TS and you control the code, Arcjet is the better default:

Fits naturally into handlers/middleware for all JS frameworks and runtimes.
ESM-first and edge-friendly.
Rules live in your codebase, reviewed and tested like everything else.
Strong primitives for bots, rate limits, WAF, email, signup flows, and PII.

Aikido makes more sense only if you’re optimizing for “one security vendor across many languages” from day zero, which is rare for typical products.

How do I tune false positives?

With Arcjet, tuning is done in code: you can log-only, branch on user, plan, route, or environment, and add conditions around rules like any other business logic. You can version and test these changes like normal code with conditionals and your existing feature flag systems.

With Aikido, most tuning is done in the dashboard and environment variables. That can be quick for small changes, but harder to keep in sync with how your application actually behaves, especially across environments.