Slack Image URL Extractor

A simple Python utility for:

• Recursively scanning a folder for Slack export JSON files
• Extracting all image URLs
• Removing duplicate URLs
• Exporting the result to output.txt

---

Project Structure

project/
│
├── scanner.py
├── extract_urls.py
├── downloader.py
├── test_scanner.py
├── test_extract_urls.py
├── test_downloader.py
├── FIX_HISTORY.md
└── README.md

---

Requirements

• Python 3.10+

No third-party packages are required.

---

Usage

1. Extract URLs from a single JSON file

python extract_urls.py messages.json

Example

python extract_urls.py "Pasted code.json"

Output

Exported 53 unique URLs.

A file named output.txt will be created.

---

2. Recursively search all JSON files in a directory and export image URLs

To recursively scan a folder for all .json files, create a separate output.txt inside each folder containing JSON files, and export all merged image URLs to the main output.txt:

python extract_urls.py ./slack_export

Or to search the current directory and all subdirectories:

python extract_urls.py .

Output

Exported 150 unique URLs.

• Each subfolder containing JSON files will get an output.txt with URLs extracted from that specific folder.
• A main output.txt containing all deduplicated image URLs across all subfolders will be created at the specified output path.

---

3. Auto-download all files to their respective parent folders

To automatically download all extracted files from output.txt into each corresponding subfolder:

python downloader.py ./slack_export

Or to download files from a single output.txt file into its containing directory:

python downloader.py ./slack_export/general/output.txt

Optional: Private Slack Token

If your Slack export URLs require private authentication headers (url_private or url_private_download), pass your token as a command-line argument or set the SLACK_TOKEN environment variable:

python downloader.py ./slack_export xoxb-your-slack-token

Or set the environment variable:

export SLACK_TOKEN="xoxb-your-slack-token"
python downloader.py ./slack_export

Output:

Downloading files from slack_export/general/output.txt...
Downloaded 15 file(s) into slack_export/general
Downloading files from slack_export/backend/output.txt...
Downloaded 30 file(s) into slack_export/backend

Completed: Downloaded 45 file(s) across 2 folder(s).

---

4. Use as a Python module

from extract_urls import extract_image_urls

urls = extract_image_urls("messages.json")

print(len(urls))

for url in urls:
    print(url)

Export directly:

from extract_urls import export_urls

count = export_urls(
    "messages.json",
    "output.txt"
)

print(count)

---

Recursively Find JSON Files

from scanner import find_json_files

json_files = find_json_files("./slack_export")

for file in json_files:
    print(file)

Example output

slack_export/general/2026-07-01.json
slack_export/general/2026-07-02.json
slack_export/random/2026-07-03.json

---

Process an Entire Slack Export

from scanner import find_json_files
from extract_urls import extract_image_urls

all_urls = set()

for json_file in find_json_files("./slack_export"):
    all_urls.update(
        extract_image_urls(json_file)
    )

with open("output.txt", "w", encoding="utf-8") as f:
    f.write("\n".join(sorted(all_urls)))

print(f"Found {len(all_urls)} unique image URLs.")

This scans every JSON file under ./slack_export and writes one deduplicated output.txt.

---

Running Unit Tests

Run every test:

python -m unittest discover

Run only the scanner tests:

python -m unittest test_scanner.py

Run only the URL extraction tests:

python -m unittest test_extract_urls.py

Run only the downloader tests:

python -m unittest test_downloader.py

Expected output

.........
----------------------------------------------------------------------
Ran 9 tests in 0.03s

OK

---

Functions

scanner.py

find_json_files(root)

Recursively finds every .json file under the specified directory.

Returns

list[pathlib.Path]

---

extract_urls.py

extract_image_urls(target_path)

Extracts all unique image URLs from a single Slack export JSON file or recursively from a directory of JSON files.

Returns

set[str]

---

export_urls(target_path, output_file="output.txt", split_by_folder=True)

Extracts all unique image URLs from a single JSON file or recursively from a directory of JSON files. When target_path is a directory and split_by_folder is True, an output.txt is created inside each subfolder containing JSON files before merging all URLs into the top-level output_file.

Returns

int

The total number of unique URLs exported to the main output file.

---

downloader.py

download_all_in_directory(root_dir, token=None)

Recursively finds all output.txt files under root_dir and downloads all files into their respective parent folders.

Returns

dict[pathlib.Path, list[pathlib.Path]]

download_urls_from_file(output_file, token=None)

Reads URLs line-by-line from output_file and downloads each file into the directory containing output_file.

Returns

list[pathlib.Path]

---

Notes

• Duplicate URLs are automatically removed.
• URLs are sorted before being written to the output file.
• The project uses only Python's standard library.
• Designed for Slack export JSON files but can be extended to support other JSON formats.