# n8n-binary-and-data-official

The skill covers how n8n stores files, images and attachments, and why binary data never crosses the agent tool boundary.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 1900 installs · ★ 554
- Author: n8n-io
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/n8n-io/skills/tree/HEAD/skills/n8n-binary-and-data-official/SKILL.md
- Updated: 2026-10-17
- HTML: https://affpapa.org/en/nevibecode/skills/n8n-binary-and-data-official

## What it does

Every n8n item has two slots: `$json` for your data and `$binary` for your files. The skill keeps one rule front and centre — file contents live in `$binary`, not `$json`, and reading them from the wrong slot is the usual mistake. To produce binary in a Code node it shows the shape to return: a `binary` object with base64 `data`, plus `mimeType` and `fileName`.

A second section deals with agent tools. Their parameters and results are JSON only, so binary cannot pass in either direction. Inbound uploads get staged in storage and the tool receives a key through `fromAi()`; outbound files get uploaded and the tool returns a URL in JSON. `passthroughBinaryImages: true` lets the model see an uploaded image, but it does not give tools access to it. Worth checking your setup if you assumed otherwise.

The skill also covers keeping binary alive after a JSON transform with a Merge node, and the storage requirement for chat surfaces: Slack, Discord or Telegram render images by URL, not from `$binary`, so the file has to sit somewhere fetchable. You configure that storage yourself; n8n does not ship one. Four reference files back it up: `references/BINARY_BASICS.md`, `references/AGENT_TOOL_BINARY.md`, `references/MERGE_FOR_CONTEXT.md` and `references/CDN_REQUIREMENT.md`.

## Requirements
- Works with: n8n

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add n8n-io/skills --skill n8n-binary-and-data-official -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/n8n-binary-and-data-official/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/n8n-binary-and-data-official/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add n8n-io/skills --skill n8n-binary-and-data-official -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/n8n-binary-and-data-official/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add n8n-io/skills --skill n8n-binary-and-data-official -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/n8n-binary-and-data-official/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install n8n-io/skills n8n-binary-and-data-official
```

2. **Manually: put the files in place**
- File: `.github/skills/n8n-binary-and-data-official/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add n8n-io/skills --skill n8n-binary-and-data-official -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/n8n-io/skills --path skills/n8n-binary-and-data-official
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/n8n-binary-and-data-official/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add n8n-io/skills --skill n8n-binary-and-data-official -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/n8n-io/skills/tree/HEAD/skills/n8n-binary-and-data-official/SKILL.md

## When to use it
- read file contents from `$binary` instead of `$json`
- build binary in a Code node and pass it downstream
- hand a user-uploaded file to an agent tool by staging it and passing a key
- return a URL for a generated file instead of raw bytes
- keep an attachment after a JSON transform by merging streams

## Example prompts
- My Code node can't see the file from the previous step. Check that I'm reading `$binary` and not `$json`.
- I need an agent tool to accept an uploaded image. Show me the pre-stage-and-pass-key pattern with `fromAi()`.
- The attachment disappeared after Edit Fields. How do I merge it back?

## Source text · SKILL.md · Apache-2.0

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: d06f582fba2b6e8a.

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````text
---
name: n8n-binary-and-data-official
description: Use when handling files, images, attachments, or binary data in n8n, OR when an AI agent needs to take a user-uploaded file as tool input or return a generated file. For Data Tables (schemas, dedup, persistent state), see the separate n8n-data-tables-official skill. Triggers on "file", "image", "PDF", "attachment", "binary", "upload", "download", chat trigger with files, agent tool that needs a file, vision/multimodal, or any handling of non-JSON file data.
---

# n8n Binary and Data

n8n handles two kinds of data: JSON (in `$json`) and binary (in `$binary`), flowing side-by-side. Binary has sharp edges around agent tools, storage, and display contexts (chat surfaces, message rendering).

For tabular storage (Data Tables), see the **`n8n-data-tables-official`** skill.

## Non-negotiables

1. **Binary is in `$binary`, not `$json`.** Don't read file contents from `$json`.
2. **Binary cannot cross the agent tool boundary in either direction.** Tool parameters are JSON only (via `fromAi()`), and tool results are JSON only. Pre-stage binary in storage and pass keys/URLs through JSON. The agent's `passthroughBinaryImages: true` lets the LLM *see* uploaded images for vision, but it does NOT enable tools to receive them. See `references/AGENT_TOOL_BINARY.md`.

## Strong defaults

- **Merge nodes keep binary in context.** When a side computation strips binary, merge it back rather than re-fetching. See `references/MERGE_FOR_CONTEXT.md`.

## Binary basics

In n8n, each item has two slots:

```ts
{
    json: { ... },           // your data
    binary: {                // your files
        data: {              // 'data' is the typical key; can be any name
            data: '<base64>',
            mimeType: 'application/pdf',
            fileName: 'invoice.pdf',
            fileExtension: 'pdf',
        },
    },
}
```

`$binary.<key>` reads the named property. Most file-handling nodes have a `binaryPropertyName` parameter, the key inside `$binary`.

### Setting binary
````
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First 2044 of 7134 bytes. © n8n-io · Apache-2.0 · https://github.com/n8n-io/skills/tree/HEAD/skills/n8n-binary-and-data-official/SKILL.md

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