Claude

Anthropic's Claude models via API, strong at coding, long documents and tool use.

Works with AI agents:llms.txtBuilt into Lovable, Replit
Ask your AI about this, with this page as the source:ChatGPT ↗Claude ↗Perplexity ↗

The Claude API is Anthropic's developer interface to its Claude models. You send text, images and PDFs and get text back, so you can add chat, document analysis, coding help or agents that call your own tools to a product. It's a separate account and bill from the Claude chat app.

The core is the Messages API: you send the conversation so far, a system prompt and optional tool definitions, and Claude replies with text or with tool calls that your code runs before sending the results back. The API keeps no conversation state between calls; you resend the history each time. Keys belong to workspaces inside an organization. Official SDKs cover Python, TypeScript (Node.js, Deno, Bun and browsers), C#, Go, Java, PHP and Ruby, plus an ant CLI.

What matters for a small team: prompt caching for long repeated context, structured outputs, extended or adaptive thinking, citations and PDF input, and the Message Batches API for bulk jobs. On top of that, the Claude Agent SDK runs the agent loop in your own process, and Managed Agents runs it on Anthropic's infrastructure. Besides Anthropic's own API, the models are available on Amazon Bedrock, Google Cloud and Microsoft Foundry.

Limits: the models are closed and run only on Anthropic's or those cloud partners' infrastructure. On Anthropic's own API, inference can be pinned to the US, but there's no EU option yet: workspace data is stored only in the US.

Where it fits

How Claude itself is built

1 tools, from its own code, website and Product Hunt page.

Who uses it

251 makers' products, each linked to the source that shows it, and 285 open-source projects that declare it in their code.

The maker says so 189Subprocessor list 72Declared in code 287How evidence is collected →
giselleGiselle is an open-source tool for building and running AI workflows in a visual node ed…

“Claude powers the intelligence behind Giselle's AI workflows. We leverage the full Claude family — Haiku for fast, cost-effective tasks on our free tier, Sonnet for balanced everyday workflows, and Opus for the most demanding reasoning challenges. Extended Thinking lets our workflows reason through multi-step problems, while multimodal capabilities enable understanding PDFs and images. The API's reliability and Claude's unique ability to follow complex instructions make it perfect for orchestrating sophisticated AI workflows. Thank you for building AI that truly thinks!”

LLM APIMaker says so +1 · source ↗
SlashyAI email client that triages the inbox and drafts replies in your voice, connected to ca…

“We chose Claude because it is strong at understanding long, messy context and producing thoughtful, natural writing. That makes it especially useful for email workflows that depend on full threads, meeting notes, and CRM history.”

LLM APIMaker says so +1 · source ↗
ZedA code editor written in Rust with multiplayer collaboration and built-in AI features li…

“We're piloting Anthropic's new Fast Edit mode for Claude 3.5 Sonnet with a small set of Zed users.”

LLM APIMaker says so +1 · source ↗
CekuraAutomated QA for Voice AI and Chat AI agents

“We use Claude models for parts of automated scenario generation, evaluation and building some of our pre-defined metrics”

LLM APIMaker says so +1 · source ↗
Skippr AIThe live AI employee inside your product, serving every user

“One of our LLM providers, using multiple for different tasks, along with our own agent skills”

LLM APIMaker says so +1 · source ↗
YouktiFinds who's ready to buy, then tells you what to do next

“Orchestrator synthesis, email scoring, coaching tips, meeting prep, weekly summaries”

LLM APIMaker says so +1 · source ↗
THEO GrowthPositioning Intelligence for brand strategists

“Claude's advanced language understanding capabilities have been instrumental in shaping THEO's context-aware AI interactions and megaprompts in chains.”

LLM APIMaker says so +1 · source ↗
AI EmailyYour AI inbox that writes like you + replies on autopilot

“Claude writes the replies that actually sound like our users. Best-in-class at tone, instruction-following, and staying safe on untrusted email content. It's why "drafts in your voice" works.”

LLM APIMaker says so +1 · source ↗
onlookOpen-source visual editor for React apps: designers edit the UI and the changes are writ…

“• Best at following nuanced design/editing instructions; fewer retries when transforming real React/Tailwind code. • High context windows make full-repo understanding practical for Onlook’s AI edits. • Reliable tool use and harmlessness out of the box reduces guardrail code we’d otherwise write. • Net: higher quality code changes without needing large amounts of prompt engineering.”

LLM APIMaker says so · source ↗
MindPalMindPal is a no-code platform for turning a person's expertise into AI agents and multi-…

“You can select Claude from Anthropic, arguably the smartest models, to power the AI agents you build on MindPal!”

LLM APIMaker says so · source ↗
ComposioGives AI agents access to 1,000+ third-party tools, handling OAuth, permissions and exec…

“The LLM engine that made it possible for the SWE agent to efficienly use tools, decide steps to be taken, and code geneartion.”

LLM APIMaker says so · source ↗
FirstQuadrantMaximize B2B sales with human-centered AI

“Claude powers some of the most nuanced and context-aware conversations in FirstQuadrant. A foundational model that we deeply rely on.”

LLM APIMaker says so · source ↗
LaunchSafeAutonomous Pentesting for Modern Applications

“The brain behind our security agents. Claude Opus reasons through code like a senior pentester — finding exploit chains, not just pattern matching. Massive context window + reliable API. Nothing else comes close.”

LLM APIMaker says so · source ↗
RunLLMAI that doesn’t just respond—it resolves

“Claude 3 Opus handles longer context and nuanced conversation better than most. Great for logs, long-form reasoning, and fallback flows. Best long-context memory and thoughtful responses.”

LLM APIMaker says so · source ↗
DataboxAgentic analytics platform for you and your agents.

“Routines run without anyone watching. That means the reasoning has to hold up on its own, no follow-up question to catch a mistake, no chance to rephrase and try again. Claude does the actual analysis behind every run: reading the data, working out what changed and why, and writing a result that has to be right the first time, because for most runs, no one checks it before it lands in someone's inbox.”

LLM APIMaker says so · source ↗

Open source: a project that declares Claude as a dependency in its public code — verifiable, but not necessarily a live product.

What makers say

152 makers on why they use Claude, in their own words on Product Hunt.

We build QA agents, so the model has to read a messy human checklist and then actually judge a page against it. Claude was the most reliable at both: it follows long, ambiguous instructions without drifting, its vision is strong enough to catch layout and copy issues in screenshots on both mobile and desktop, and it returns structured output we can pin to a specific element instead of vague prose. Tool use held up across long agent runs, which matters when twenty agents sweep an entire site at once. It also had the lowest rate of confidently wrong findings in our testing, and false positives are what kill trust in a QA tool.
Superflow AISep 2026 ↗
Claude powers the intelligence behind Giselle's AI workflows. We leverage the full Claude family — Haiku for fast, cost-effective tasks on our free tier, Sonnet for balanced everyday workflows, and Opus for the most demanding reasoning challenges. Extended Thinking lets our workflows reason through multi-step problems, while multimodal capabilities enable understanding PDFs and images. The API's reliability and Claude's unique ability to follow complex instructions make it perfect for orchestrating sophisticated AI workflows. Thank you for building AI that truly thinks!
giselleSep 2026 ↗
I actually use both. GPT runs parts of our generation pipeline. But Claude got the reasoning layer, because every API in FetchSandbox ships a brain that has to read a real integration failure, reproduce it, and reason about whether a fix actually held. That's judgment, not autocomplete. MCP being Anthropic's protocol sealed it. FetchSandbox is MCP-native, so Claude Code users drive our tools directly with no copy-paste. Honestly, a lot of FetchSandbox got built in Claude Code too.
FetchSandboxSep 2026 ↗
Relaticle's assistant needs to call 37 CRM tools in one turn and get the arguments right, and Claude has been the most reliable at that in real use. Prompt caching on our long system prompt cut cost and latency enough to run it as the default. Effort levels let us tune each turn. MCP is Anthropic's protocol, so Claude Desktop and Claude Code connect to Relaticle as first-class clients. OpenAI and Gemini stay in the model catalog as options; Claude is the default.
RelaticleSep 2026 ↗
Claude's Opus and Sonnet are our primary models for agentic query - the part of Unabyss that reasons and synthesizes across a user's entire context. That's the hardest thing we ask a model to do, and Claude handles long-context reasoning and multi-step synthesis better than the alternatives we've run it against. Being multi-provider, we don't have to use Claude here - we choose to, because the output quality on this specific job is worth it.
UnabyssSep 2026 ↗

Loved and watch-outs

Themes that recur in makers' words and Hacker News comments, each linked to what it summarises, with how Product Hunt tags its reviews.

Most loved
  • It is strong at writing code and powers many code generation and coding agent products. PHPH 2PH 3PH 4
  • It stays coherent through long, multi-step reasoning and agent workflows. PHPH 2PH 3PH 4
  • Its writing sounds natural and matches a user's tone rather than reading as AI-generated. PHPH 2PH 3PH 4
  • Makers trust its instruction-following and safety on untrusted content. PHPH 2PH 3
Watch-outs
  • Outages are frequent, with uptime below three nines across the API and apps. HNHN 2HN 3HN 4
  • API pricing is a large multiple of subscription pricing, making heavy agent use expensive. HNHN 2HN 3
  • Postmortems confirmed periods of degraded output, including a lowered default reasoning effort in Claude Code. HN
  • Watermarking applied to all output and hidden request marking in Claude Code upset developers. HNHN 2
On Product Hunt 5.0★ · 1,012 reviews
AI assistant 108code generation 70contextual understanding 35reasoning capabilities 32data analysis 22nuanced responses 19creative writing 18ethical AI 15message limits 10typography issues 10contextual understanding 2conversation search 2limited image output 2
Read the reviews on Product Hunt ↗

Reliability and open issues

Incidents on its status page50+ in the last 90 days, 21 major · 50+ in the last yearFrom its own status page, 2026-10-02. Vendors decide what they post; one page can cover several products.

Who switches

Public pull requests on GitHub since Oct 2024 whose title says "X to Y" — real code changes moving a project from one tool to another, by developers in general. Open a row to see the pull requests.

OpenAI API → Claude127 PRs
Gemini API → Claude108+ PRs
Groq → Claude10 PRs
DeepSeek → Claude8 PRs
Claude → Gemini API105+ PRs
Claude → OpenAI API89 PRs
Claude → DeepSeek17 PRs
Claude → Groq15 PRs

Alternatives to Claude

All alternatives by situation →

On Product Hunt, people weigh it against: Claude Code, Grok API.

Questions makers ask about Claude

Does Anthropic train on data I send through the API?

No, not by default. Inputs and outputs from commercial products, including the API, aren't used for training unless you report feedback or otherwise opt in. source ↗

How long are API prompts and responses kept?

Anthropic deletes API inputs and outputs from its backend within 30 days. The exceptions are data in features you keep yourself (such as the Files API), a zero-data-retention agreement, usage-policy enforcement, and legal requirements. source ↗

Can I control where my data is processed and stored?

Partly. You can set inference_geo per request or as a workspace default to keep inference on US infrastructure (Claude 4.6 and later models), but the workspace storage location can't be changed after creation, and "us" is currently the only option. source ↗

Can I send PHI and sign a BAA?

Yes. Anthropic offers a BAA for HIPAA-ready services, including the first-party API. Your organization's Primary Owner signs it and then asks sales or your Anthropic contact to enable it, and it covers only that one organization. source ↗

Can I call Claude with the OpenAI SDK?

Yes, through a compatibility layer, but some fields are silently ignored. For example, strict tool schemas aren't enforced, audio input isn't supported, and thinking output isn't returned. For PDFs, citations, prompt caching and full thinking, Anthropic points you to the native API. source ↗

How do rate limits and spend caps work?

Limits are set per organization and depend on a usage tier that rises automatically with usage history. Each tier below Custom has a monthly spend cap; when you hit it, requests return 429 until the next month unless you ask for a higher limit. source ↗

Is there a batch mode for large offline jobs?

Yes. The Message Batches API takes up to 100,000 requests or 256 MB per batch, usually finishes within an hour, and cuts costs by 50%. Batches expire after 24 hours, and results stay downloadable for 29 days. source ↗

Which languages have an official SDK?

Python, TypeScript, C#, Go, Java, PHP and Ruby, plus the ant command-line tool. source ↗

Is Claude free?

No permanent free tier; paid use starts at Pay per token. source ↗

Is Claude open source or self-hostable?

Not open source, and hosted only.

Can AI coding agents work with Claude?

It serves an llms.txt docs index; Lovable, Replit set it up natively.

Who uses Claude?

251 makers' products we track, each with a source, and 285 open-source projects declare it in their code. source ↗