Convert Word to Markdown

Upload a Word document (.docx) and get clean, readable Markdown back instantly — with headings, lists, tables, and text styling preserved. No installation, no account required.

Why convert Word to Markdown?

A .docx file is full of formatting metadata - font settings, margins, style definitions - that add no value for a language model but still cost tokens. Markdown keeps the content structure (headings, tables, lists) in a compact format that models like ChatGPT, Claude, and Gemini handle far better.

How does it work?

Upload your Word file (.docx) or drag it into the converter.
slim-down reads the document structure and converts headings, bold and italic text, lists, and tables into the matching Markdown syntax.
Download or copy the resulting Markdown, ready to paste straight into a prompt.

Open Converter

Frequently Asked Questions

Does the formatting of my Word document stay intact?

The content structure is preserved: headings (Heading 1 through 4), bold and italic text, lists, and tables are recognized and converted to Markdown syntax. Visual styling like fonts, colors, and margins is dropped - that's by design, since an AI model doesn't need that information.

What happens to images in my Word document?

Images aren't carried over; slim-down converts only the textual content. For a language model, plain text is usually what you want to feed it anyway - images cost a lot of tokens and most models can't reconstruct the exact text from them regardless.

Is converting Word to Markdown free?

Yes. Without an account you get up to 3 free conversions per day. A free account gives you unlimited conversions and lets you save and sync documents across devices.

Do tables in my Word document stay intact?

Yes. Unlike PDF, for example, a .docx file has an explicit table structure, which slim-down converts directly into clean Markdown tables with rows and columns preserved.

🔑 REST API Access & Keys

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Securely sync documents across all your devices.

⚡ REST API Endpoints

POST /api/convert

Tekst, CSV, JSON, HTML, YAML

Converts input to Markdown or another target format. Optionally add save: true to automatically save the result to your account.

curl -X POST https://slim-down.nl/api/convert \
  -H "Authorization: Bearer <JOUW_API_SLEUTEL>" \
  -H "Content-Type: application/json" \
  -d '{
    "input": "Product,Prijs\nLaptop,999",
    "source_format": "csv",
    "target_format": "markdown"
  }'

POST /api/convert-file

.pdf, .docx, .doc, .pptx, .ppt, .xlsx, .xls, .ipynb, .srt, .vtt

Upload PDF, Word, PowerPoint, Excel, Jupyter Notebook, or subtitle (.srt/.vtt) files via multipart form-data for direct conversion to Markdown or CSV.

curl -X POST https://slim-down.nl/api/convert-file \
  -H "X-API-Key: <JOUW_API_SLEUTEL>" \
  -F "[email protected]"

GET /api/documents

Cloud Sync

Retrieves all your saved documents in JSON format for sync across apps and devices.

curl -X GET https://slim-down.nl/api/documents \
  -H "Authorization: Bearer <JOUW_API_SLEUTEL>"

GET /api/auth/me

User Info & Token Validation

Checks if your API key is valid and returns user profile information.

curl -X GET https://slim-down.nl/api/auth/me \
  -H "Authorization: Bearer <JOUW_API_SLEUTEL>"

🤖 AI Integrations & Token Reduction Examples

Claude • Gemini • Copilot

Convert documents or raw data via slim-down to compact Markdown before sending them as context to an LLM to save tokens and costs.

⚡ Claude Tool / Skill (Function Calling) (Anthropic Tool Use schema & Python handler)

Give Claude the skill/tool to automatically call the slim-down API when it needs to simplify a document, table, or JSON/HTML:

Anthropic Console ↗

import requests
from anthropic import Anthropic

SLIM_DOWN_KEY = "JOUW_SLIM_DOWN_API_SLEUTEL"
SLIM_DOWN_URL = "https://slim-down.nl/api/convert"

# 1. Definieer de slim-down Skill / Tool voor Claude
tools = [
    {
        "name": "slim_down_convert",
        "description": "Converteert HTML, JSON, YAML, CSV, Word of platte tekst naar compacte Markdown om tokens te besparen.",
        "input_schema": {
            "type": "object",
            "properties": {
                "content": {
                    "type": "string",
                    "description": "De ruwe tekst, html, json, yaml of csv content"
                },
                "target_format": {
                    "type": "string",
                    "enum": ["markdown", "json", "yaml", "csv", "excel", "text"],
                    "default": "markdown"
                }
            },
            "required": ["content"]
        }
    }
]

# 2. Tool handler functie
def run_slim_down_tool(content: str, target_format: str = "markdown") -> str:
    resp = requests.post(
        SLIM_DOWN_URL,
        headers={"Authorization": f"Bearer {SLIM_DOWN_KEY}"},
        json={"input": content, "target_format": target_format}
    )
    return resp.json().get("result", "")

# 3. Claude aanroepen met de tool
client = Anthropic()
response = client.messages.create(
    model="claude-3-7-sonnet-20250219",
    max_tokens=1024,
    tools=tools,
    messages=[
        {
            "role": "user",
            "content": "Kun je deze HTML tabel versimpelen naar Markdown?\n<table><tr><th>Naam</th><th>Score</th></tr><tr><td>Alex</td><td>95</td></tr></table>"
        }
    ]
)
print("Tool calls:", response.content)

💬 System Prompts & AI Instructions (Claude Projects, Custom GPTs & Cursor rules)

Use this prompt in your Claude Project Custom Instructions, System Prompt, or .cursorrules:

Claude Projects ↗ • Custom GPTs ↗

### SYSTEM PROMPT / AI INSTRUCTION:
You have access to the slim-down conversion API at https://slim-down.nl.
When the user asks to analyze large HTML pages, Word files (.docx), Excel sheets (.xlsx), JSON data, or CSV:
1. Use the slim-down API endpoint (POST /api/convert or POST /api/convert-file)
   with header "Authorization: Bearer <YOUR_SLIM_DOWN_KEY>".
2. Always convert the input to "markdown" first to minimize token consumption.
3. Answer the user's question solely based on the resulting clean Markdown.

🟣 Anthropic Claude (Direct SDK) (Python Anthropic SDK + Document Context)

First upload your Word/Excel/JSON file to slim-down and send the clean Markdown context directly to Claude 3.5 / 3.7:

Anthropic Docs ↗

import requests
from anthropic import Anthropic

SLIM_DOWN_KEY = "JOUW_SLIM_DOWN_API_SLEUTEL"
CLAUDE_KEY = "sk-ant-..."

# 1. Converteer Word/Excel naar compacte Markdown via slim-down
with open("jaarverslag.docx", "rb") as f:
    res = requests.post(
        "https://slim-down.nl/api/convert-file",
        headers={"X-API-Key": SLIM_DOWN_KEY},
        files={"file": f}
    )
clean_markdown = res.json()["result"]

# 2. Stuur de geoptimaliseerde context naar Claude
client = Anthropic(api_key=CLAUDE_KEY)
message = client.messages.create(
    model="claude-3-7-sonnet-20250219",
    max_tokens=1000,
    messages=[
        {
            "role": "user",
            "content": f"Analyseer dit document en geef de 3 belangrijkste KPI's:\n\n{clean_markdown}"
        }
    ]
)
print(message.content[0].text)

🔵 Google Gemini (Python google-genai / google-generativeai SDK)

Optimize spreadsheets or raw tables into Markdown tables for Gemini 2.0 / 1.5 Flash:

Google AI Studio ↗

import requests
import google.generativeai as genai

SLIM_DOWN_KEY = "JOUW_SLIM_DOWN_API_SLEUTEL"
genai.configure(api_key="AIzaSy...")

# 1. Converteer complexe spreadsheet of CSV data naar Markdown tabel
raw_csv = (
    "Afdeling,Q1,Q2,Budget\n"
    "Sales,120000,145000,250000\n"
    "Marketing,45000,60000,100000"
)
conv = requests.post(
    "https://slim-down.nl/api/convert",
    headers={"Authorization": f"Bearer {SLIM_DOWN_KEY}"},
    json={"input": raw_csv, "source_format": "csv", "target_format": "markdown"}
).json()

# 2. Vraag Gemini om samenvatting met minimale tokens
model = genai.GenerativeModel("gemini-2.0-flash")
response = model.generate_content(
    f"Hier zijn de kwartaalcijfers in Markdown:\n\n{conv['result']}\n\nWelke afdeling benadert zijn budget?"
)
print(response.text)

🤖 GitHub Copilot, Cursor & ChatGPT (Prompt Engineering & Context Injection)

Copy the converted Markdown directly into your IDE or Copilot Chat window with the following structured prompt template:

OpenAI Platform ↗ • Copilot ↗

You are an AI assistant. Use the specification below (converted via slim-down)
as the source of truth for the implementation.

### SOURCE DOCUMENT (Markdown):
{{PASTE CONVERTED SLIM-DOWN OUTPUT HERE}}

### INSTRUCTIONS:
Write the required Go / TypeScript dataclasses and validation rules based on the tables above.

🐍 🟨 Python & JavaScript Integration Examples

Python (requests)

import requests

headers = {
    "Authorization": "Bearer JOUW_API_SLEUTEL",
    "Content-Type": "application/json"
}
payload = {
    "input": "# Titel\nInhoud converteren",
    "target_format": "html"
}
res = requests.post("https://slim-down.nl/api/convert", json=payload, headers=headers)
print(res.json()["result"])

JavaScript / Node.js (fetch)

const res = await fetch("https://slim-down.nl/api/convert", {
  method: "POST",
  headers: {
    "Authorization": "Bearer JOUW_API_SLEUTEL",
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    input: "Product,Prijs\nBoek,15.00",
    target_format: "markdown"
  })
});
const data = await res.json();
console.log(data.result);