rate-limiting

A Phoenix web-app feature that limits requests by IP address and repeated failed logins by email. Phoenix is a web framework for Elixir applications.

In plain words
What is it for?
Use it to throttle endpoints and cap repeated failed password attempts, using Hammer and proxy-aware client-IP detection.
Why use it?
It slows down excessive traffic and credential-guessing attempts, reducing abuse of routes and login forms.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/fullstack-phoenix/saas_kit/rate-limiting
Any agent
npx skills add fullstack-phoenix/saas_kit --skill rate-limiting
Clone the repo
git clone --depth 1 https://github.com/fullstack-phoenix/saas_kit

Made for: Claude Code, Codex.

Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,100 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00043 $0.01100
Opus 5 $0.00022 $0.00550
Sonnet 5 $0.00009 $0.00220
Haiku 4.5 $0.00004 $0.00110

Measured yesterday against content hash bfa07cef199f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

rate-limiting scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/rate-limiting/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Rate limiting

Adds IP- and login-based rate limiting to a Phoenix app using Hammer with the ETS backend. Installs RemoteIp for proxy-aware client IP extraction, stores the normalized IP in conn.private, and provides a MyApp.RateLimit module for IP-based throttling. It also wraps the email/password login action so repeated failed attempts for the same email are capped at 8 per minute.

When to use

  • The app needs to limit how often an IP can hit a route or endpoint.
  • You want to slow down credential-stuffing / brute-force login attempts.
  • Don't reach for this if the app already sits behind an upstream rate limiter (API gateway, Cloudflare) that covers the same routes.

Dependencies

  • Requires: authentication (the login limit wraps the generated UserSessionController).
  • Recommended: None.

Install

mix saaskit.feature.install rate_limiting

No install decisions. The installer adds remote_ip and hammer to mix.exs, generates the IP extractor plug and the MyApp.RateLimit module, plugs IP extraction into the endpoint, and rewrites the login action to check the limit.

What it generates

  • lib/my_app_web/plugs/client_ip_extractor.exMyAppWeb.Plugs.ClientIPExtractor, resolves the real client IP via RemoteIp and stores it in conn.private as :remote_ip_tuple and :remote_ip_string.
  • lib/my_app/rate_limit.exMyApp.RateLimit (use Hammer, backend: :ets), exposes limit_by_ip/2, limit_login/2, and client_ip/1; usable as a plug.
  • lib/my_app_web/endpoint.ex — plugs ClientIPExtractor right after Plug.RequestId.
  • lib/my_app_web/controllers/user_session_controller.ex — the email/password login helper now calls RateLimit.limit_login/2 before checking credentials, denying after 8 attempts per email per 60 seconds.
  • mix.exs — adds {:remote_ip, "~> 1.2"} and {:hammer, "~> 7.4"}.

Configuration

No config keys. Limits are passed as options at the call site. The defaults baked into MyApp.RateLimit are:

Read the full file on GitHub · 116 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 116 lines · 43 tokens per session scan A bfa07cef199f

Subscribe to this mod's changes

rate-limiting is a skill published in the GitHub repository fullstack-phoenix/saas_kit (2 stars, last pushed 2mo ago), licensed MIT. It adds 43 tokens to every session and 1,100 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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