catalogue / tools / Documents / PDF to Markdown API

PDF to Markdown API

Converts a PDF to Markdown, inferring headings from font size (best-effort, not layout-perfect; no OCR).

Endpoint
POST /v1/pdf-to-markdown
Price
$0.005 per call
Family
Documents

01When to use it

  • A PDF has no heading structure, only sized glyphs; recovering Markdown needs a real PDF engine plus a hardened fetch, which an agent cannot do inline without walking past the SSRF controls. Offline, best-effort text-layer extraction; no OCR. No external CMap or standard-font data is configured or fetched. PDFs with self-contained character mappings can yield text, including CJK; documents requiring unavailable predefined CMaps can return empty or partial text without an error. Embedded ToUnicode alone does not guarantee extraction when the encoding still needs an external CMap. Missing standard-font data does not necessarily prevent extraction. A successful response does not certify complete text; truncated reports only the max_pages limit.
  • Your source is PDF and you need Markdown.

When not to use it

  • The input is over 25 MB (26,214,400 bytes): pdf-to-markdown answers too_large (413).
  • The destination needs more than 40 s to answer: the call ends with upstream_timeout (424).
  • The destination is on a private or local network: the network guard refuses it with blocked_target (403).

02Parameters

FieldTypeRequiredDescription
urlstringyesAbsolute http(s) URL of the PDF, up to 2048 characters; redirects are followed and the body must start with the %PDF- signature.
max_pagesintegernoHow many leading pages to convert, 1 to 1000; a shorter document is not an error, and a longer one is cut and reported as truncated. Default: 100.

03Limits

LimitValue
Largest source file25 MB (26,214,400 bytes)
Timeout40 s
Source formatsPDF
Output formatsMarkdown

04Example

The published example of pdf-to-markdown, verbatim: the request body and the response it returns.

Request
POST /v1/pdf-to-markdown
content-type: application/json
payment-signature: <base64 x402 payload>

{
  "url": "https://grist.tools/samples/documents/markdown-guide.pdf",
  "max_pages": 100
}
Response
200 OK
payment-response: <base64 settlement receipt>

{
  "source_url": "https://grist.tools/samples/documents/markdown-guide.pdf",
  "total_pages": 1,
  "extracted_pages": 1,
  "truncated": false,
  "chars": 249,
  "markdown": "# Field Notes\n\n## A short guide in three parts\n\nThis sample shows how headings are inferred.\n\nLarger text becomes a heading, body text stays plain.\n\n### Second section\n\nEach line of the page becomes its own block.\n\nThe document ends after this line."
}

Sample file: documents/markdown-guide.pdf. One-page PDF with lines drawn at 24, 18, 14 and 12 pt Helvetica, so a 12 pt body sits under three heading sizes; built with pdf-lib with pinned metadata.

In the sample itself, the PDF 1.7 file has 3 top-level objects, 1 object stream among them, and a cross-reference stream; inflated, its streams declare 1 page with MediaBox 0 0 420 320, base font Helvetica and 7 text runs at 24, 18, 12 and 14 pt, the first reading "Field Notes". The returned Markdown splits into 7 blocks separated by blank lines, with 3 headings (1 at level 1, 1 at level 2, 1 at level 3) reading "Field Notes", "A short guide in three parts" and "Second section". Plain paragraphs make up 4 blocks, the first reading "This sample shows how headings are inferred." and the last "The document ends after this line." Its headings total 10 words, its paragraphs 31 words.

Response fieldTypeIn the example
source_urlstring"https://grist.tools/samples/documents/markdown-guide.pdf"
total_pagesnumber1
extracted_pagesnumber1
truncatedbooleanfalse
charsnumber249
markdownstring"# Field Notes ## A short guide in three parts This sample shows how headings are inferred. Larger text becomes a heading, body text stays plain. ### Second section Each line of the page becomes its own block. The document ends after this line."

05Call it from code

JavaScript
// pdf-to-markdown: $0.005 per call, paid in USD Coin on eip155:8453 via x402
// Install: npm install @x402/fetch@2 @x402/evm@2 viem@2
// Save as client.mjs (ES module, Node 18+), export EVM_PRIVATE_KEY with the paying wallet's key in your shell, then run: node client.mjs
// The wrapper reads the 402 (payment-required), signs and retries with payment-signature.
import { wrapFetchWithPayment, x402Client, decodePaymentResponseHeader } from '@x402/fetch'
import { ExactEvmScheme } from '@x402/evm/exact/client'
import { privateKeyToAccount } from 'viem/accounts'

const account = privateKeyToAccount(process.env.EVM_PRIVATE_KEY)
const client = new x402Client().register('eip155:8453', new ExactEvmScheme(account))
const fetchWithPayment = wrapFetchWithPayment(fetch, client)

const body = {
  "url": "https://grist.tools/samples/documents/markdown-guide.pdf",
  "max_pages": 100
}

const res = await fetchWithPayment('https://grist.tools/v1/pdf-to-markdown', {
  method: 'POST',
  headers: { 'content-type': 'application/json' },
  body: JSON.stringify(body),
})
console.log(res.status, await res.json())
const settle = res.headers.get('payment-response')
if (settle) console.log(decodePaymentResponseHeader(settle).transaction)
Python
# pdf-to-markdown: $0.005 per call, paid in USD Coin on eip155:8453 via x402
# Install: pip install "x402[requests,evm]>=2.24,<3"
# The session reads the 402 (payment-required), signs and retries with payment-signature.
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http import decode_payment_response_header
from x402.http.clients.requests import x402_requests
from x402.mechanisms.evm.exact import register_exact_evm_client
from x402.mechanisms.evm.signers import EthAccountSigner

account = Account.from_key(os.environ["EVM_PRIVATE_KEY"])
client = x402ClientSync()
register_exact_evm_client(client, EthAccountSigner(account), networks="eip155:8453")
session = x402_requests(client)

payload = {
    "url": "https://grist.tools/samples/documents/markdown-guide.pdf",
    "max_pages": 100
}

res = session.post("https://grist.tools/v1/pdf-to-markdown", json=payload)
print(res.status_code, res.json())
settle = res.headers.get("payment-response")
if settle:
    print(decode_payment_response_header(settle).transaction)
curl
# pdf-to-markdown: $0.005 per call, paid in USD Coin on eip155:8453 via x402
# 1. Unpaid call: HTTP 402, the requirements in the payment-required header (base64 JSON) and in the body.
curl -i -X POST 'https://grist.tools/v1/pdf-to-markdown' -H 'content-type: application/json' -d '{"url":"https://grist.tools/samples/documents/markdown-guide.pdf","max_pages":100}'

# 2. Same call with the signed payment (an EIP-3009 authorization, EIP-712 signed: it cannot be
#    typed by hand). x-payment is accepted as the v1 alternative. HTTP 200 carries payment-response.
curl -i -X POST 'https://grist.tools/v1/pdf-to-markdown' -H 'content-type: application/json' -H 'payment-signature: <base64 x402 payload>' -d '{"url":"https://grist.tools/samples/documents/markdown-guide.pdf","max_pages":100}'

06Errors

CodeHTTPFor this service
invalid_input400The body does not match the schema; its fields are url and max_pages.
blocked_target403
unreachable_target424
upstream_timeout424
unsupported_content_type415The source is not a type pdf-to-markdown reads; it reads PDF.
too_large413
unprocessable422
internal500

Input that is rejected before the tool runs (malformed JSON, schema mismatch, body over the size limit) is never charged.

When each code is raised, and what it means for payment: /docs/pdf-to-markdown.

07Conversions

ConversionRecorded sampleSource sizeOutput size
PDF to Markdowndocuments/markdown-guide.pdf1.1 KB249 bytes

08Questions

How much does a pdf-to-markdown call cost?
$0.005 per call, paid in USDC on Base via x402, with no account and no API key.
What does pdf-to-markdown return?
A JSON object with 6 top-level fields: source_url, total_pages, extracted_pages, truncated, chars and markdown. The example on this page is a real call over documents/markdown-guide.pdf.
What happens when a pdf-to-markdown call fails?
The tool answers with a typed JSON error from the errors table. Payment is settled only after the tool has produced its result; a call that fails inside the tool is never settled. A 503 upstream_unavailable can follow a settled call; the x402 payments guide covers it, 429, 402 and an uncertain 500.

09Related