How to Create and Secure a Perplexity API Key

# Current terminal session only
export PERPLEXITY_API_KEY="your_api_key_here"

# Make it permanent (zsh, the macOS default)
echo 'export PERPLEXITY_API_KEY="your_api_key_here"' >> ~/.zshrc
source ~/.zshrc

# Current PowerShell session only
$env:PERPLEXITY_API_KEY = "your_api_key_here"

# Save for your user account (open a new window afterwards)
setx PERPLEXITY_API_KEY "your_api_key_here"

# pip install perplexityai python-dotenv
from dotenv import load_dotenv
from perplexity import Perplexity

load_dotenv()            # loads PERPLEXITY_API_KEY from .env
client = Perplexity()    # reads the key from the environment

reply = client.chat.completions.create(
    model="sonar",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(reply.choices[0].message.content)

curl https://api.perplexity.ai/v1/sonar \
  -H "Authorization: Bearer $PERPLEXITY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"sonar","messages":[{"role":"user","content":"Say hello"}]}'

// server.js (Node 18+, Express). The key stays on the server.
import express from "express";
const app = express();
app.use(express.json());

app.post("/api/ask", async (req, res) => {
  const question = String(req.body.question || "").slice(0, 1000);
  const r = await fetch("https://api.perplexity.ai/v1/sonar", {
    method: "POST",
    headers: {
      "Authorization": `Bearer ${process.env.PERPLEXITY_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ model: "sonar", messages: [{ role: "user", content: question }] }),
  });
  const data = await r.json();
  res.json({ answer: data.choices?.[0]?.message?.content, citations: data.citations });
});

app.listen(3000);