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Claude Code: what it is and how developers actually use it

Claude Code is Anthropic's AI agent that codes in your terminal. Here's what it really is, how much it costs, and the concrete techniques senior engineers apply.

Anthropic charges $20 to $200/month for Claude Code. Plan mode, CLAUDE.md, skills and validation loops: what senior devs keep and what they work around.

The developer obsession with Claude Code is not a passing trend. On Hacker News, engineers are asking how to manage their dependency on the tool. On Twitter, parallel multi-terminal sessions have become an informal norm. What's happening isn't simply the adoption of a new code generation tool: it's a deep shift in how work gets done, and one that's hard to reverse.

  • 🚀 Claude Code runs in the terminal, shifting the developer's role from writing code to architecting tasks.
  • 💡 A well-maintained CLAUDE.md file saves dozens of minutes of context on every new session.
  • ⚠️ Without a multi-phase plan and context window management, large features inevitably drift off course.
  • ✅ Skills (markdown playbooks) let you encode a repeatable engineering process that the agent follows on every invocation.

What is Claude Code? (the short version)

Claude Code is an AI agent developed by Anthropic that runs directly in your terminal. Unlike GitHub Copilot or Cursor, which complete your code in the IDE line by line, Claude Code can read your entire codebase, modify multiple files simultaneously, run your tests, interpret errors, and retry until it reaches the objective you set. That's the difference between an autocomplete and an autonomous agent.

Pricing: Claude Code is included in a Claude.ai subscription starting at $20/month (Pro plan). For intensive professional use, meaning multi-hour sessions during a workday, the Max plan ($100 to $200/month) is recommended: Pro hits its quota limits after about 1.5 to 2 hours of sustained work.

According to Anthropic, teams that adopt it report a 20 to 55% reduction in time per task and 3 to 5x faster prototyping, figures from their own internal studies that should be weighed against your specific context and codebase maturity.

Why Claude Code isn't a glorified autocomplete

The first thing that surprises you when reading developer feedback on Claude Code is that nobody talks about the model first. They talk about the terminal.

Cursor and GitHub Copilot live in the IDE. They complete code before your eyes, in a visual context where you see every change applied in real time. That proximity creates a posture of constant supervision: you stay in control of the keyboard and intervene at every step. Claude Code operates in the terminal. You describe an objective, submit it, and the agent works. Code scrolls by, often too fast to follow line by line.

This form factor produces an important psychological effect. Developers who use Claude Code behave less like code reviewers and more like task architects. Their role shifts from writing to problem formulation, plan validation, and defining clear constraints. This isn't a regression, it's a move up in abstraction.

The other reason behind this obsession comes down to positioning. Non-technical solutions like Replit or Lovable typically don't show the code. They target people who don't want to see it. On the other end, Cursor and Copilot assume you're watching every line produced. Claude Code occupies a middle ground: you stay in your development environment, you can intervene at any time, but you're not forced to supervise everything. A developer can run Claude Code, work on something else, and come back to a functional change. That's exactly what non-technical users can't do, and what IDE tools don't offer.

On terminal coding benchmarks, Claude Code is no longer at the top as of this writing. But its users aren't leaving. The quality of Anthropic's models, combined with this terminal positioning, created a first-mover adoption advantage that's hard to undo. And crucially, Claude Code doesn't present itself as a developer replacement: it positions itself as a tool that amplifies technical developers. An engineer doesn't fight a tool they don't perceive as a threat to themselves.

Since March 2026, an official VS Code extension is available on the Microsoft marketplace, with a dedicated sidebar, inline diffs, and one-click change acceptance. Senior developers overwhelmingly stick to the terminal interface, precisely because the absence of a GUI enforces the architect posture described above.

For a deeper look at this role shift, read our analysis on AI agents and developers.

The CLAUDE.md file: the starting point most people skip

Claude Code has no memory between sessions. Every time you open a new context, the agent starts from scratch. Without structure, that means you'll spend the first few minutes re-explaining the project, code conventions, build commands, and your preferences. Over a dense work week, that's an hour lost per day.

The answer to this problem is the CLAUDE.md file, placed at the root of your project and automatically loaded into context at every session. Think of it as an onboarding document written for an engineer who shows up every morning with no memory of the day before.

An effective CLAUDE.md covers three areas. What the project does, with a short functional description. Where key files live, with explicit paths to important components. And how the work gets done: commands to run tests, build the project, run it locally, naming conventions, expected commit style, and constraints specific to your stack.

Size matters. A file of 100 to 200 lines maximum is the target. Beyond that, the model dilutes its attention and important constraints are less reliably followed. Stick to what matters, be specific, and skip introductory paragraphs that add nothing for the agent. Some developers even add a description of their own profile to calibrate the response style.

Complement this setup with custom slash commands, saved in .claude/commands/. A pr-summary command that auto-generates a pull request description, a review-component command to audit a component against your internal criteria. Any workflow you repeat more than once a week deserves to be encoded.

Another strongly recommended habit: the /clear command between each distinct task. Claude Code's context window is finite. When it fills up, decision quality degrades. The agent starts ignoring constraints established at the beginning of the session and produces code that's inconsistent with earlier decisions. Treating each task as a fresh session feels counterintuitive, but it's the approach that preserves quality over time.

The multi-phase plan: tackling large features without drowning

Developers who use Claude Code on complex features have all made the same discovery: letting the agent code a large feature in a single session is a bad idea. The context window fills up, initial decisions get lost in the noise, and architectural coherence takes a hit.

The answer is the multi-phase plan. Before writing a single line of code, activate plan mode (shift-tab in Claude Code). The agent explores the codebase, asks clarifying questions about what's ambiguous in your specification, and returns a structured plan broken into independent phases.

This clarification process is worth the time investment. A session of 10 to 40 questions on a complex feature might seem inefficient. In reality, it unblocks unknowns that would have cost far more to fix during implementation. Stress-test your idea before building it: that's an engineering principle that long predates AI, and it applies here with redoubled effectiveness.

Once you have the plan in hand, check your context window consumption before launching execution. If you're at 80% free after the planning phase, you can chain several phases in the same session. If planning consumed more, slice finer and switch sessions between phases.

To preserve the plan across multiple context windows, create a GitHub issue that contains it. The agent can fetch this issue in a new session and pick up exactly where it left off. This cloud storage offers a secondary advantage: your teammates can see what's happening, comment, and pick up the work if you're unavailable.

Structure execution phases as vertical slices: each phase cuts through all layers of the application rather than covering a complete horizontal layer. One phase that creates an engine with tests, another that integrates the UI layer on top, rather than a separate "backend" phase and "frontend" phase. Vertical slices catch integration problems early. Horizontal slices accumulate them until the end.

Skills and the validation loop: encoding your engineering process

A skill in Claude Code is a markdown file that encodes an engineering process the agent must follow when invoked. It's not a quick one-off command. It's a playbook that can reference other files, delegate to sub-agents, and enforce a non-negotiable sequence of steps.

Here are the skills that consistently show up among senior engineers:

Skill When to invoke What it enforces
Grilling Before any feature development Exhaustive interview to surface unknowns
PRD to issues After writing a specification document Breakdown into tasks with blocking dependencies
TDD Implementing new modules Strict red-green-refactor loop
Architecture Regular review or after a development sprint Identifying and deepening shallow modules

The grilling skill forces the agent to interview the developer branch by branch, dependency by dependency, before touching any code. It's not the agent that decides what's ambiguous: the skill mandates that it systematically hunt for ambiguities.

The TDD skill enforces a red-green-refactor loop. The agent writes a failing test, then writes the minimal code to make it pass, then looks for refactoring opportunities. This workflow has an important prerequisite: your codebase must have clear module boundaries. If boundaries are fuzzy, the agent improvises its own test perimeters, which produces inconsistent results.

The architecture skill forces the agent to explore the codebase for shallow modules that would benefit from being deepened. It generates multiple alternative designs for the same module, in parallel via sub-agents, and compares them. This regular exploration, once a week on an active codebase, maintains structural quality as the code grows.

The validation loop is arguably the technique with the best value-to-effort ratio. You configure in CLAUDE.md that the agent must run the build, tests, and type-checker after every modification. If anything fails, the agent treats it as a blocker and fixes it before moving on. You can launch a session, step away for 20 minutes, and come back to code that self-validated along the way. The difference in quality is striking.

These techniques are part of a broader trend described in our article on what's really changing for developers with AI.

What this changes in daily practice

All of these techniques form a coherent method. You start with a solid CLAUDE.md that eliminates the need to re-explain the project every session. You use plan mode and a grilling skill to clarify what you're building before writing a single line. You structure execution in vertical phases with GitHub issues as external memory. You add a validation loop so the agent catches and fixes its own mistakes. You encode your repeatable processes into invocable skills.

This isn't a checklist of features to tick off. It's a change in posture: moving from writing code to formulating well-defined problems for an agent that's capable but memoryless. The quality of what the agent produces is directly correlated with the quality of your structure, not the quality of your individual prompts. A well-architected codebase with a solid CLAUDE.md and precise skills produces significantly better code than a disorganized codebase with elaborate prompts.

Tools will keep evolving quickly, and Claude Code itself may be surpassed on benchmarks within months. But the principles behind these techniques (explicit context management, structured plans, validation loops, process encoding) are engineering invariants that will outlast the tools. Invest in the method, not in mastering a specific interface.

What Claude Code doesn't do well (yet)

Quota limits are the most common complaint. On the Pro plan, intensive sessions of 1.5 to 2 hours can exhaust the quota. For serious full-day work, the Max plan isn't a luxury.

The risk of blind delegation is real. Documented cases include unintentional file deletion, broken dependencies, and overly aggressive commits. The validation loop described above is designed to mitigate this risk, but it doesn't replace a final human review on any structural change.

Large codebases create coherence problems. On projects with hundreds of thousands of lines, the agent can lose the global architectural thread during a long session. Slicing into vertical phases with the plan stored in GitHub issues is the practical answer.

Gradual dependency is the least measured medium-term risk. Systematically delegating weakens certain reflexes for reading and writing code directly. Some teams are beginning to structure "no-agent" session rotations to preserve their technical autonomy.

Frequently asked questions about Claude Code

What exactly is Claude Code? It's an AI agent developed by Anthropic that runs in your terminal (or in VS Code since March 2026). It reads your codebase, modifies multiple files, runs your tests, interprets errors, and retries autonomously until it reaches the objective you set.

What's the difference between Claude Code and Cursor or GitHub Copilot? Cursor and Copilot live in the IDE and complete your code line by line. Claude Code is an autonomous terminal agent: you give it a high-level objective, and it executes a complete plan without you supervising every change. You shift from the role of coder to task architect.

How much does Claude Code cost? Claude Code is included in a Claude.ai subscription. The Pro plan starts at $20/month. For intensive professional use, the Max plan ($100 to $200/month) is recommended, as Pro hits its quota limits on long sessions.

Do you need to be an experienced developer to use Claude Code? The tool explicitly targets technical profiles. The quality of what it produces depends directly on your structure (CLAUDE.md, plan mode, project architecture), not on the sophistication of your prompts. A junior developer on a disorganized codebase will get disappointing results.

Can Claude Code replace a developer? No, and that's actually its explicit positioning. Anthropic targets developers as amplifiers, not non-developers as standalone users. Architecture decisions, business context management, and final review remain human responsibilities.

Vincent Roye
Vincent Roye
CEO & Founder, GoLive Software

French engineer based in Vietnam since 2014. He leads a team of senior full-stack developers and has helped startups and SMEs structure their tech teams for over 11 years.