Grok 4.5 が登場：コーディング、エージェント型ワークフロー、API 料金、そして Chat4O で Grok を試せる場所

Grok 4.5 was released on July 16, 2026, with a clear professional focus: coding, agentic tasks, engineering, and knowledge work. For developers, the important changes are not just higher model capability. The release combines a 500,000-token context window, image input, configurable reasoning, function calling, structured outputs, and an API designed for long-running technical work.

The practical access story has two parts. Developers can use the official grok-4.5 API through xAI now. Readers who want to explore related Grok conversations in a browser can use Chat4O AI, although Chat4O does not yet have a verified Grok 4.5 model page or selector.

Grok 4.5 Release Features: What Changed and What Is Confirmed

Grok 4.5 is a released production model rather than a preview. The official xAI announcement identifies July 16, 2026, as the launch date and describes the model as xAI's strongest option for coding, agentic work, and professional knowledge tasks. The official API identifier is grok-4.5.

The model's verified specifications make that positioning more concrete:

The context window matters most when a task contains a large repository, many technical documents, or a long interaction history. It does not guarantee perfect retrieval across every position in a prompt, so teams should still test how accurately the model finds requirements, code references, and contradictory evidence at realistic context sizes.

Image input broadens the model beyond text-only coding. A developer can combine a bug report with an interface screenshot, a diagram with implementation notes, or a chart with a request for structured analysis. The output remains text, which makes Grok 4.5 more suitable for analysis and agent control than for direct image generation.

xAI publishes extensive benchmark results, but those figures should be read as release evidence rather than a universal ranking. The company's own charts show Grok 4.5 leading some engineering evaluations and trailing other systems on others. Harnesses, reasoning settings, context, tools, and task selection all affect the outcome. For a software team, a private evaluation set built from actual tickets and repositories is more useful than a single leaderboard position.

Grok 4.5 for Coding Agents and Long-Running Engineering Work

Grok 4.5 is best understood as an engineering model that can participate in a process, not merely answer a coding question. xAI says its reinforcement-learning work emphasized multi-step software engineering and other technical tasks, while Grok Build turns that model capability into a terminal-based coding agent.

The strongest use cases are tasks with several dependent steps:

• Analyze an unfamiliar repository before proposing edits.
• Trace a failing test across multiple modules.
• Compare an implementation with a product specification or screenshot.
• Refactor a subsystem while preserving its external behavior.
• Generate focused tests, run them, inspect failures, and revise the patch.
• Research current package documentation before planning an upgrade.
• Review a pull-request diff and identify risky assumptions.
• Coordinate specialist subagents for exploration, implementation, and review.

Grok Build is the practical agentic layer. Its current feature set includes plan mode, subagents, reusable skills, hooks, MCP servers, repository conventions through AGENTS.md, persistent memory, code search, multi-file editing, Git integration, terminal execution, code review, sandboxed execution, and headless operation for CI/CD. Grok 4.5 is the default model in that environment.

This distinction helps teams choose the right surface. Use the Grok 4.5 API when you are building your own orchestration, permissions, tool registry, or product experience. Use Grok Build when you want an existing coding-agent interface in the terminal. Use an ordinary browser chat when the work is primarily explanation, planning, brainstorming, or one-off code review.

Long agent loops still need operational controls. Limit which tools can modify production systems, require review for destructive actions, isolate untrusted code, and record tool calls. A model can be capable while still making an incorrect assumption about a repository or command. The more autonomy an agent receives, the more important scoped credentials, checkpoints, tests, and rollback paths become.

Grok 4.5 API Pricing, Reasoning Controls, and Integration Basics

The Grok 4.5 API uses two pricing tiers based on prompt length. According to the live xAI pricing documentation, short-context requests cost $2 per million input tokens,$0.30 per million cached-input tokens, and $6permillionoutputtokens\mathrm{.}Onceapromptreach$4, 12 respectively.

xAI states that when a request reaches the long-context threshold, long-context rates apply to all tokens in that request. This makes context design a cost decision. Do not send an entire repository on every turn when retrieval, file selection, summarization, or context compaction can provide the necessary evidence more efficiently.

Reasoning effort is configurable as low, medium, or high, with high used by default. Low effort can suit classification, extraction, simple transformations, or fast conversational responses. High effort is more appropriate for difficult debugging, architecture decisions, or multi-step engineering, but it may use more time and tokens. Measure accepted results at each setting rather than assuming maximum reasoning is always economical.

A basic Responses API request looks like this:

curl https://api.x.ai/v1/responses \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "grok-4.5",
    "reasoning": {"effort": "high"},
    "input": "Inspect this bug description, propose the smallest safe fix, and list the tests that should prove it."
  }'

For agentic systems, function calling and structured outputs are more consequential than free-form prose. Define narrow tools, validate arguments, use JSON Schema for machine-consumed responses, and return clear tool errors that the model can recover from. The official documentation also recommends stable prompt-cache routing for conversations and context compaction for long tool-heavy loops.

Production evaluation should track first-token latency, total task time, prompt and completion tokens, cache-hit rate, tool-call validity, retries, JSON-schema compliance, test results, and human correction time. The most useful metric is cost per accepted workflow, not price per million tokens in isolation. Server-side tools may also add invocation charges, so include those costs when testing web search, code execution, file retrieval, or other hosted tools.

Grok 4.5 vs Grok 4.3 and Grok 4: What to Use on Chat4O

Grok 4.5 is the strongest choice when a project specifically needs xAI's newest coding and agentic model, but that does not make every earlier Grok workflow obsolete. Model choice depends on the surface, the task, and what is actually available.

Conceptually, Grok 4.5 shifts the emphasis from advanced chat toward sustained engineering execution. Grok 4 and Grok 4.3 remain relevant reference points for reasoning, coding support, long-form analysis, and browser conversations. However, a Chat4O response from Grok 4.3 should not be presented as a Grok 4.5 result, and the versions should not be treated as interchangeable.

Chat4O is useful as a low-friction place to explore related Grok workflows before committing to an API integration. A developer can test prompt structure, compare how available models explain code, or see whether a browser chat fits a research task. When the requirement is specifically Grok 4.5, official xAI access is the verified route today.

Chat4O is an independent third-party platform. Its live pages, model selector, subscription terms, and usage limits can change separately from xAI. As of July 23, 2026, a dedicated Chat4O Grok 4.5 model page or selectable Grok 4.5 session could not be verified. The safest publishing language is therefore "explore related Grok models on Chat4O," not "use Grok 4.5 on Chat4O."

For an honest comparison, run the same task with the same source material and score factual correctness, code quality, instruction following, structured-output validity, latency, and revision effort. This reveals whether switching improves the workflow that matters, rather than merely changing the model name.

Grok 4.5 FAQ and Final Recommendation

When was Grok 4.5 released?

xAI released Grok 4.5 on July 16, 2026. The official announcement and developer documentation describe it as available through the xAI API, Grok Build, and additional listed integrations.

What is the Grok 4.5 API model ID?

The official model ID is grok-4.5. xAI also documents grok-4.5-latest and grok-build-latest aliases, but production teams should verify alias behavior before relying on it for reproducible evaluations.

Does Grok 4.5 support images?

Yes. The official model page lists text and image input with text output. That supports screenshot, diagram, chart, and document-image analysis, but it does not mean the model directly returns generated images.

How much does the Grok 4.5 API cost?

Below 200,000 prompt tokens, published prices are $2 per million input tokens,$0.30 per million cached-input tokens, and $6permillionoutputtokens\mathrm{.}Atorabovethethreshold,th$4, 12.

Is Grok 4.5 available on Chat4O?

A dedicated Grok 4.5 page or live selector on Chat4O was not verified for this review. Chat4O currently provides indexed pages for Grok 4.3 and Grok 4, which are useful for related browser-based testing but are not substitutes for verified Grok 4.5 access.

Should developers switch to Grok 4.5?

Teams building coding agents, repository-scale analysis, multimodal engineering tools, or long-running knowledge workflows should test it. Switching makes sense only when controlled trials show better accepted-task rate, lower review effort, or a stronger cost-to-completion ratio than the current model.

Final recommendation

Grok 4.5 is the clearest xAI choice for API-based coding, agentic workflows, and demanding engineering work. Use the official API when the application specifically requires Grok 4.5, and use Grok Build when a terminal coding agent is the desired product surface.

For browser exploration, Chat4O Grok 4.3 is the newest currently verified dedicated Grok page, while Chat4O AI Chat is the more flexible comparison starting point. Recheck the live model selector before publication because a dedicated Grok 4.5 option may appear later.

Related reading

• Discover Grok 4 AI on Chat4O
• Grok 4 vs GPT-5: Which AI Fits Your Workflow?
• Grok Imagine in 2026: xAI News and Where to Try Grok
• Introducing Grok 4.5
• Grok 4.5 developer overview