How to Access, Install & Use Claude: A Complete Guide

·

Jon Imms
Claude guide

Updated: September 2025

Claude (by Anthropic) is a powerful AI assistant that shines at long-form writing, code generation/refactoring, and complex reasoning. In this guide, I’ll walk you through accessing Claude on web/desktop/mobile, getting API keys, installing the CLI (“Claude Code”), and then using it with Node.js, Python, PHP (WordPress), cURL, and React. You’ll also find real developer workflows, prompt recipes, cost controls to stay under a $70/month budget, troubleshooting tips, and security best practices. If you’re a WordPress developer (like me), there’s a full WP section with examples you can ship today.

Who this is for: web developers, content teams, and anyone who wants a practical, copy-pasteable Claude setup that goes from zero to productive fast.

Table of Contents

What is Claude? Models & Use Cases

Claude is Anthropic’s family of large-language models optimized for safe, helpful, and steerable behavior. For developers and content teams, the big wins are: structured long-form writing, code generation/refactoring, data extraction/transformation, and multi-step reasoning. Anthropic ships multiple model tiers to balance speed, capability, and price.

Model (example)StrengthWhen to useNotes
Claude 3.5 HaikuSpeed + low costDrafts, boilerplate, bulk transformsGreat for early iterations and batch prompts
Claude 3.5 SonnetBalancedDaily driver for code + writingBest default for most tasks
Claude 3.5 OpusDeep reasoningHard problems, critical refactorsUse sparingly to control cost

Typical dev use cases: generating unit tests, porting code, writing migrations, optimizing queries, writing docs/READMEs, reviewing PR diffs, shaping content with brand voice, and helping with “explain like I’m 5 (but precise)” debugging.

How to Access Claude (Web, Desktop, Mobile)

For chat-style usage (no code), you can use Claude in the browser, desktop apps, or mobile. This is perfect for content creation, brainstorming, and quick code help.

PlatformStepsTips
WebVisit claude.ai, sign inPin in your bookmarks. Great for fast drafts.
DesktopDownload for macOS/Windows from Anthropic; sign inUse global shortcuts and quick paste workflows
MobileInstall iOS/Android app; sign inGreat for idea capture on the go

Screenshot placeholders: Insert your own captures of the sign-in page, model picker, and a sample project thread so readers see what to expect.

Get API Access & Keys

To integrate Claude into your apps and scripts, you’ll need an API key from the Anthropic console. This takes 2–3 minutes:

  • Sign in at console.anthropic.com
  • Open Settings → API keys
  • Create a new key and copy it (store securely)
  • Optionally set usage caps/alerts

Pro tip: never hard-code keys. Use environment variables, a .env file (never committed), or your platform’s secrets manager.

Install & Configure the Claude CLI (“Claude Code”)

The CLI lets you generate, refactor, document, and reason about code right from the terminal—no copy/paste dance. It’s perfect for “change this function, explain that query, write tests” workflows.

Prerequisites

  • Node.js 18+ (check with node -v)
  • Anthropic API key saved as ANTHROPIC_API_KEY

Install

# Global install
npm install -g @anthropic-ai/claude-code

# Verify
claude --version

# Set your key (macOS/Linux)
export ANTHROPIC_API_KEY="<your_key>"

# Windows PowerShell
setx ANTHROPIC_API_KEY "<your_key>"

First run (quick feel)

# Ask Claude to write a Bash backup script
claude --model claude-3.5-sonnet "Write a bash script that zips a folder and logs to stdout"

# Refactor a file to PSR-12 (example)
claude --refactor src/MyClass.php --model claude-3.5-sonnet

# Document a module with docblocks and README snippets
claude --document src/ --model claude-3.5-haiku

Tip: When experimenting, start with Haiku (faster, cheaper). If the result needs deeper reasoning, re-run with Sonnet or Opus.

Hello, Claude: Your First Calls (Node, Python, cURL)

Pick your stack. Below are minimal, copy-pasteable samples that you can run immediately.

Node.js (Official SDK)

# 1) Install
npm install @anthropic-ai/sdk

# 2) Save a script (ask.js)
# node ask.js "Write a SQL query to get top 10 customers by revenue"
/* ask.js */
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  apiKey: process.env.ANTHROPIC_API_KEY,
});

async function main() {
  const userPrompt = process.argv.slice(2).join(" ") || "Say hello.";
  const res = await client.messages.create({
    model: "claude-3.5-sonnet",
    max_tokens: 300,
    messages: [{ role: "user", content: userPrompt }],
  });
  console.log(res.content?.[0]?.text || JSON.stringify(res, null, 2));
}
main().catch(err => {
  console.error(err);
  process.exit(1);
});
# 3) Run
ANTHROPIC_API_KEY=sk-... node ask.js "Generate a Dockerfile for a Node 20 + pnpm app"

Python (Official SDK)

# 1) Install
pip install anthropic
# ask.py
import os
from anthropic import Anthropic

client = Anthropic(api_key=os.getenv("ANTHROPIC_API_KEY"))

def ask(prompt: str, model: str = "claude-3.5-sonnet", max_tokens: int = 300):
    res = client.messages.create(
        model=model,
        max_tokens=max_tokens,
        messages=[{"role": "user", "content": prompt}],
    )
    return res.content[0].text

if __name__ == "__main__":
    print(ask("Write a JS debounce function with explanation."))

cURL (Fast sanity check)

curl https://api.anthropic.com/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "content-type: application/json" \
  -d '{
    "model": "claude-3.5-haiku",
    "max_tokens": 200,
    "messages": [
      {"role": "user", "content": "Generate a POSIX shell script to tail logs and colorize errors."}
    ]
  }'

WordPress + Claude: PHP Snippets & Secure Patterns

For WP developers, here are battle-tested patterns to call Claude safely from PHP (and to wire it into admin tools or custom endpoints). These examples use wp_remote_post() and environment variables.

Minimal PHP helper

<?php
/**
 * Ask Claude with a prompt string.
 * Store ANTHROPIC_API_KEY in wp-config.php (putenv) or server env.
 */
function bt_claude_ask( string $prompt, string $model = 'claude-3.5-sonnet', int $max_tokens = 400 ) : string {
    $api_key = getenv('ANTHROPIC_API_KEY');
    if ( ! $api_key ) {
        return 'Missing ANTHROPIC_API_KEY';
    }

    $response = wp_remote_post( 'https://api.anthropic.com/v1/messages', array(
        'headers' => array(
            'x-api-key'    => $api_key,
            'content-type' => 'application/json',
        ),
        'timeout' => 30,
        'body'    => wp_json_encode( array(
            'model'     => $model,
            'max_tokens'=> $max_tokens,
            'messages'  => array(
                array( 'role' => 'user', 'content' => $prompt ),
            ),
        ) ),
    ) );

    if ( is_wp_error( $response ) ) {
        return $response->get_error_message();
    }
    $code = wp_remote_retrieve_response_code( $response );
    if ( $code < 200 || $code >= 300 ) {
        return 'HTTP ' . $code . ': ' . wp_remote_retrieve_body( $response );
    }
    $body = json_decode( wp_remote_retrieve_body( $response ), true );
    return $body['content'][0]['text'] ?? 'No content';
}

Secure key storage

// wp-config.php
putenv('ANTHROPIC_API_KEY=sk-...');

Alternatively, set environment variables at the web server level (preferred in managed hosting). Never commit keys to Git.

Admin tool: “Ask Claude” metabox (quick utility)

<?php
add_action('add_meta_boxes', function() {
    add_meta_box('bt-claude', 'Ask Claude (Draft Helper)', function() {
        ?>
        <textarea style="width:100%;height:120px" id="bt-claude-prompt"></textarea>
        <button class="button button-primary" id="bt-claude-run">Ask</button>
        <pre id="bt-claude-out" style="margin-top:8px;white-space:pre-wrap"></pre>
        <script>
        (function($){
          $('#bt-claude-run').on('click', function(){
            const prompt = $('#bt-claude-prompt').val();
            $.post(ajaxurl, { action: 'bt_claude_ajax', prompt }, function(res){
              $('#bt-claude-out').text(res.data || res);
            });
          });
        })(jQuery);
        </script>
        <?php
    }, ['post','page'], 'side', 'high');
});

add_action('wp_ajax_bt_claude_ajax', function(){
    if ( ! current_user_can('edit_posts') ) {
        wp_send_json_error('No permission', 403);
    }
    $prompt = sanitize_textarea_field($_POST['prompt'] ?? '');
    wp_send_json_success( bt_claude_ask($prompt) );
});

This creates a handy “Ask Claude” tool in your editor sidebar for quick outlines or code snippets. It respects WP capabilities and keeps the key on the server.

WP REST endpoint (headless, React frontends)

<?php
add_action('rest_api_init', function() {
  register_rest_route('bt/v1', '/claude', [
    'methods'  => 'POST',
    'permission_callback' => function(){ return current_user_can('edit_posts'); },
    'callback' => function( WP_REST_Request $req ) {
        $prompt = sanitize_textarea_field( $req->get_param('prompt') );
        return rest_ensure_response( [ 'output' => bt_claude_ask( $prompt ) ] );
    }
  ]);
});

Pair this with a React editor UI or a custom dashboard widget to build internal writing/coding assistants.

Frontend Example: React + API Route

For modern frontends (Next.js, Remix, Vite), put your key on the server and expose a minimal API route. Here’s a simple pattern:

Client component

import { useState } from "react";

export default function ClaudeDemo() {
  const [loading, setLoading] = useState(false);
  const [result, setResult] = useState("");

  async function handleAsk() {
    setLoading(true);
    const res = await fetch("/api/claude", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ prompt: "Propose 3 UX improvements for a blog homepage" }),
    });
    const data = await res.json();
    setResult(data.output || "No result");
    setLoading(false);
  }

  return (
    <div>
      <button disabled={loading} onClick={handleAsk}>{loading ? "Thinking..." : "Ask Claude"}</button>
      <pre>{result}</pre>
    </div>
  );
}

API route (Node)

// /api/claude.js (or /app/api/claude/route.ts in Next.js)
import Anthropic from "@anthropic-ai/sdk";

export default async function handler(req, res) {
  try {
    const { prompt } = req.body || {};
    const client = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY });
    const out = await client.messages.create({
      model: "claude-3.5-sonnet",
      max_tokens: 400,
      messages: [{ role: "user", content: prompt || "Say hi." }],
    });
    res.status(200).json({ output: out.content?.[0]?.text || "" });
  } catch (e) {
    console.error(e);
    res.status(500).json({ error: "Server error" });
  }
}

Security: Never call Anthropic directly from the browser (it would expose your key). Always proxy through a server route or WP Ajax/REST handler.

Real Dev Workflows You Can Copy

1) Playwright: stabilize flaky tests

Paste failing tests with logs and ask Claude: “Identify brittle selectors and rewrite using robust queries; add waits; suggest retries only when necessary; explain rationale.” Iterate with error output. Works great for cookie banners, route timing, and dynamic DOM.

2) Gravity Forms automation

Have Claude draft webhook handlers, validation callbacks, and admin notices. Provide your exact field IDs, sample payloads, and business rules so it generates code that compiles cleanly with your plugin structure.

3) WooCommerce: API & webhooks

Feed Claude your order meta & webhook docs; ask for a secure signing/verification snippet and retry logic. Then have it produce a Postman collection or a Node script for local testing.

4) theme.json & design tokens

Paste your theme.json and Figma design tokens, ask Claude to normalize font sizes, rationalize color scales, and generate an editor-styles.css scaffold. It’s great at consistent naming and pruning unused settings.

5) Content pipeline

  • Outline in chat (Haiku)
  • Draft long-form (Sonnet)
  • Technical accuracy pass with your code snippets (Sonnet/Opus)
  • SEO meta & social cards (Haiku)
  • Final polish with your brand voice (Sonnet)

Prompt Engineering: Templates That Work

Claude responds best to clear goals, constraints, and examples. Below are modular templates you can paste into chat or API calls.

Code refactor (PSR-12, typed, documented)

ROLE: Senior PHP engineer. Apply PSR-12. Add types. Add concise docblocks.
GOAL: Refactor this class for readability and testability. Keep public API stable.
CONSTRAINTS:
- Do not introduce frameworks.
- Keep method names stable.
- Add unit-testable seams.
INPUT:
<paste code here>
OUTPUT:
- Refactored code block
- Notes explaining changes
- Suggestions for tests

Content long-form (developer audience)

AUDIENCE: Senior WordPress developers
TONE: Practical, no fluff
GOAL: 1200-word tutorial on building a WP REST endpoint for a React frontend
INCLUDE: Code blocks, screenshots list, pitfalls and fixes, performance notes
STYLE: Headings, lists, short paragraphs
END WITH: Checklist + FAQ

Data extraction (structured JSON)

Task: Extract fields into JSON (valid, minified).
Schema:
{"title":"","author":"","date":"","links":[],"code_blocks":0}
Text:
<paste text>
Return: JSON only.

Stay Under $70/mo: Cost Controls & Monitoring

Most teams can stay well under $70/month per person with a few habits:

  • Right-size the model: Haiku for drafts/boilerplate; Sonnet for daily use; Opus sparingly.
  • Cap tokens: set max_tokens per call (e.g., 200–400 for code edits; 600–900 for long answers).
  • Constrain context: avoid dumping entire repos; give just the files/functions needed.
  • Batch wisely: ask for 3 options in one call instead of 3 separate calls.
  • Monitor usage: check the Anthropic console weekly; set internal alerts at 70–80% of budget.

Cost playbook

ScenarioModelToken strategyNotes
Draft outlineHaikumax_tokens: 250Fast iterations
Refactor a functionSonnetmax_tokens: 400Include function + tests only
Complex reviewOpusmax_tokens: 600–900Use after Haiku/Sonnet baseline

Troubleshooting & Common Errors

SymptomLikely causeFix
401 UnauthorizedBad/missing API keySet env var; restart shell; verify in console
CLI not foundGlobal bin not in PATHAdd npm bin -g to PATH; reinstall
Slow/expensive callsToo much context or Opus by defaultTrim inputs; switch to Haiku/Sonnet; cap tokens
Weird formattingPrompt too vagueAdd required format, examples, and constraints
Security concernsKey used client-sideProxy via server; rotate keys

Security, Compliance & Team Governance

  • Never expose keys client-side. Proxy through server routes or WP Ajax/REST.
  • Add allowlists for origins and authenticated roles when exposing internal endpoints.
  • Use a secrets manager (Vercel/Netlify secrets, GCP Secret Manager, AWS Secrets Manager, Kinsta/Render env vars).
  • Rotate keys quarterly; revoke on role changes.
  • Create a team policy doc: what data can/can’t be sent to LLMs; what to review before publishing.
  • Log usage (who, when, why) for internal transparency and cost control.

FAQ

Do I need the CLI if I already use the web app?

No, but the CLI is a force multiplier for code: refactors, tests, doc generation, and quick transforms directly in your repo—without losing context.

How do I keep results consistent?

Lower temperature (0.1–0.4), supply style guides/examples, and keep prompts deterministic (“Return a single JSON object with keys X, Y, Z”).

Can I use Claude to review PRs?

Yes. Feed the diff (or key files), add repo conventions, and ask for a structured review: security issues, performance risks, naming, and specific, actionable changes.

Conclusion & Next Steps

You now have everything to access, install, and use Claude across web, desktop, and code. Start with Haiku for speed, move to Sonnet for daily development, and reserve Opus for truly hard problems. Wire the API into your WordPress projects using secure server-side handlers, and lean on the CLI for hands-on refactors and documentation. With sane token caps and model choices, staying under a $70/month budget is absolutely doable.

Quick Checklist

  • Create an account & log into claude.ai
  • Generate an API key in the console
  • Install the CLI and verify with claude --version
  • Run the Node/Python hello-world
  • Integrate a WP Ajax/REST endpoint for internal tools
  • Adopt the cost playbook and set a monthly alert
  • Document team policies around data and usage

Want a downloadable starter repo (Node + WP + CLI scripts) to match this post? Tell me your preferred structure and I’ll assemble it for your stack.

Comments

Leave a Reply

Your email address will not be published. Required fields are marked *