Quickstart

From sign-up to your first evaluated flag in under 5 minutes.

Set up in the dashboard

1. Sign up at app.redpennon.dev and choose a plan.
2. Create an organisation — you'll be prompted on first login.
3. Create a project — from your organisation dashboard, click New Project.
4. Copy your API key — go to Project → Environments, open the environment you want (e.g. development), and copy the API Key UUID.
5. Create a feature flag — click New Feature, choose type Release, give it a slug (e.g. dark-mode). RedPennon seeds an on/off variable and enables targeting in Development automatically.

Make your first evaluation

Pick your language and paste in the API key you copied above.

Node.js

npm install @redpennon/node-sdk

import { RedPennonClient } from "@redpennon/node-sdk";

const client = new RedPennonClient({ apiKey: process.env.RP_API_KEY! });

const enabled = await client.variableValue("dark-mode", false, {
  user: { id: "user-123" },
});

console.log(enabled); // true or false

Python

pip install redpennon

from redpennon import Client, UserContext

with Client(api_key="YOUR_API_KEY") as client:
    enabled = client.variable_value(
        "dark-mode",
        default=False,
        user=UserContext(id="user-123"),
    )
    print(enabled)  # True or False

Go

go get github.com/redpennon/sdks/go

package main

import (
    "context"
    "fmt"
    "os"

    redpennon "github.com/redpennon/sdks/go"
)

func main() {
    c := redpennon.NewClient(os.Getenv("RP_API_KEY"))
    value, _ := c.VariableValue(context.Background(), "dark-mode", false, &redpennon.UserContext{
        ID: "user-123",
    })
    fmt.Println(value) // true or false
}

cURL

curl -X POST "https://api.redpennon.dev/v1/variables/dark-mode" \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"user": {"id": "user-123"}}'

The response is true (the on variation) because the starter rule enables the flag for all users in Development. Flip the targeting toggle off in the dashboard and re-evaluate — you'll get false.

What's next

• Feature flags guide — feature types, variables, and variations
• Targeting rules guide — user properties, audience conditions, rollout schedules
• Environments guide — per-environment defaults and API keys
• API reference — full endpoint, auth, and error docs