Airtable Attachment Public URL: Fix Expiring File Links

If you pull an attachment from the Airtable API, the URL looks public. You can paste it in a browser, download the image, and pass it to another service. Then a few hours later, the same URL breaks.

That is expected behavior. Airtable attachment download URLs are temporary. Airtable's own support docs say these direct download URLs expire after a short time and should not be used as long-lived public file links. If you need a stable URL, the file needs to be copied somewhere else.

Why Airtable Attachment URLs Break

Airtable attachments have two useful URL shapes:

• Attachment viewer URLs. These open inside Airtable and require access to the base or interface.
• Attachment download URLs. These can be opened directly, but they expire after a short time.

The direct download URL is the one developers usually grab from the API. It often lives on an airtableusercontent.com domain. It is useful for immediate processing, but it is not a CDN URL and it is not meant to be stored forever.

Airtable currently says download URLs stay active for at least 2 hours after receiving them. That is enough for an automation step. It is not enough for a website, client portal, email campaign, invoice PDF, or database field that needs to keep working next week.

The Fix: Store Your Own Public URL

The clean fix is to add a second field in Airtable, usually a URL or long text field, and store a permanent hosted copy there.

Example fields:

Python Script: Airtable Attachment to Permanent URL

This script reads records from Airtable, downloads the first attachment in a field, uploads it to FilePost, and writes the public URL back to Airtable.

import os
import requests

AIRTABLE_TOKEN = os.environ["AIRTABLE_TOKEN"]
AIRTABLE_BASE_ID = os.environ["AIRTABLE_BASE_ID"]
AIRTABLE_TABLE = "Assets"
AIRTABLE_ATTACHMENT_FIELD = "Attachment"
AIRTABLE_PUBLIC_URL_FIELD = "Public URL"

FILEPOST_API_KEY = os.environ["FILEPOST_API_KEY"]


def airtable_headers():
    return {
        "Authorization": f"Bearer {AIRTABLE_TOKEN}",
        "Content-Type": "application/json",
    }


def list_records():
    url = f"https://api.airtable.com/v0/{AIRTABLE_BASE_ID}/{AIRTABLE_TABLE}"
    response = requests.get(url, headers=airtable_headers(), timeout=30)
    response.raise_for_status()
    return response.json()["records"]


def download_attachment(attachment):
    response = requests.get(attachment["url"], timeout=60)
    response.raise_for_status()
    return response.content, attachment.get("filename", "airtable-file")


def upload_to_filepost(file_bytes, filename):
    response = requests.post(
        "https://filepost.dev/v1/upload",
        headers={"X-API-Key": FILEPOST_API_KEY},
        files={"file": (filename, file_bytes)},
        timeout=120,
    )
    response.raise_for_status()
    return response.json()


def update_airtable_record(record_id, public_url, file_id):
    url = f"https://api.airtable.com/v0/{AIRTABLE_BASE_ID}/{AIRTABLE_TABLE}/{record_id}"
    payload = {
        "fields": {
            AIRTABLE_PUBLIC_URL_FIELD: public_url,
            "FilePost ID": file_id,
        }
    }
    response = requests.patch(url, headers=airtable_headers(), json=payload, timeout=30)
    response.raise_for_status()


def main():
    for record in list_records():
        fields = record.get("fields", {})

        if fields.get(AIRTABLE_PUBLIC_URL_FIELD):
            continue

        attachments = fields.get(AIRTABLE_ATTACHMENT_FIELD, [])
        if not attachments:
            continue

        file_bytes, filename = download_attachment(attachments[0])
        uploaded = upload_to_filepost(file_bytes, filename)

        update_airtable_record(
            record["id"],
            uploaded["url"],
            uploaded["file_id"],
        )

        print(f"{record['id']} -> {uploaded['url']}")


if __name__ == "__main__":
    main()

Environment Variables

export AIRTABLE_TOKEN="pat..."
export AIRTABLE_BASE_ID="app..."
export FILEPOST_API_KEY="fh_..."

Run the script soon after the Airtable URL is generated. If the download URL has already expired, request the record from Airtable again to get a fresh attachment URL.

Automation Version

The same flow works in Zapier, Make, n8n, or Pipedream:

1. Trigger on a new or updated Airtable record.
2. Use the attachment download URL from the trigger payload.
3. Download the file into the automation step.
4. Upload the binary file to FilePost.
5. Update the Airtable record with the returned url.

The important detail is timing. Treat the Airtable URL as an input to the workflow, not the final URL you store or send to users.

When This Is Worth Doing

This pattern is useful when Airtable is acting as the internal database, but another system needs a stable public file URL:

• A public website that renders images from Airtable records
• A client portal that links to PDFs uploaded by your team
• An email automation that includes file links
• A CRM or support tool that needs attachment URLs without Airtable login
• An n8n or Zapier workflow that passes file URLs to another API

If everyone opening the file already has Airtable access, an Airtable viewer URL may be enough. If the file has to work outside Airtable, copy it to a file host and store the hosted URL.

References

• Airtable attachment URL behavior
• Permanent URLs for Airtable attachments
• n8n binary file to public URL workflow