README

1. replace `!!!` everywhere with meaningful values
   - your cookie in the fetch headers
   - your tokens in the fetch URLs
   grab them from your browser devtools network tab and copy the requests as nodejs fetch commands to make it easy
   
2. first run `node scrape_archived.js`
3. then run `./scrape.sh`

FYI it only scrapes the archived messages of your saved items (saved messages has 3 possible states: in-progress, complete, and archived)

package.json

{
  "type": "module",
  "name": "slack-scrape",
  "version": "1.0.0",
  "description": "",
  "main": "scrape.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC"
}

scrape.sh

#!/bin/zsh

node scrape_msgs.js
while [[ $? -ne 0 ]]; do
    echo sleeping...
    sleep 60
    node scrape_msgs.js
done

scrape_archived.js

import fs from "fs"

const d = console.log

const HEADERS = {
  "accept": "*/*",
  "accept-language": "en-GB,en-US;q=0.9,en;q=0.8,hu;q=0.7",
  "content-type": "multipart/form-data; boundary=----WebKitFormBoundary7VmY11kTIBACOPhl",
  "sec-ch-ua": "\"Google Chrome\";v=\"117\", \"Not;A=Brand\";v=\"8\", \"Chromium\";v=\"117\"",
  "sec-ch-ua-mobile": "?0",
  "sec-ch-ua-platform": "\"macOS\"",
  "sec-fetch-dest": "empty",
  "sec-fetch-mode": "cors",
  "sec-fetch-site": "same-site",
  "sec-gpc": "1",
  "cookie": "!!!"
}

const getSavedItems = async (limit = 5, cursor = null, filter = 'saved') => {
  return await (await fetch("https://cppftw.slack.com/api/saved.list?!!!", {
    "headers": HEADERS,
    "referrerPolicy": "no-referrer",
    "body": `------WebKitFormBoundary7VmY11kTIBACOPhl
}
Content-Disposition: form-data; name=\"token\"

!!!
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"limit\"

${limit}
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"filter\"

${filter}${ cursor ? `
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"cursor\"

${cursor}` : ''}
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"include_tombstones\"

true
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"_x_reason\"

saved-api/savedList
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"_x_mode\"

online
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"_x_sonic\"

true
------WebKitFormBoundary7VmY11kTIBACOPhl
Content-Disposition: form-data; name=\"_x_app_name\"

client
------WebKitFormBoundary7VmY11kTIBACOPhl--`,
    "method": "POST"
  })).json()
}

let msgs = new Set()

let response = null
let cursor = null
do {
  d('call with', {cursor})
  response = await getSavedItems(50, cursor, 'archived')
  // d(response)
  d(`got ${response['saved_items'].length} msgs:`, response['saved_items'])
  response['saved_items'].forEach(msg => {
    msgs.add(JSON.stringify(msg))
  })
  cursor = response['response_metadata']['next_cursor']
} while (cursor)

// d(JSON.stringify(Array.from(msgs)))

fs.writeFileSync('archived.json', JSON.stringify(Array.from(msgs).map(msg => JSON.parse(msg)), null, 2));
d(msgs.size)

scrape_msgs.js

import fs from "fs"
import {execSync} from "child_process"

const HEADERS = {
  "accept": "*/*",
  "accept-language": "en-GB,en-US;q=0.9,en;q=0.8,hu;q=0.7",
  "content-type": "multipart/form-data; boundary=----WebKitFormBoundaryuCFwDhhrnEFlx8a8",
  "sec-ch-ua": "\"Google Chrome\";v=\"117\", \"Not;A=Brand\";v=\"8\", \"Chromium\";v=\"117\"",
  "sec-ch-ua-mobile": "?0",
  "sec-ch-ua-platform": "\"macOS\"",
  "sec-fetch-dest": "empty",
  "sec-fetch-mode": "cors",
  "sec-fetch-site": "same-site",
  "sec-gpc": "1",
  "cookie": "!!!"
}

const d = console.log

let msgs = JSON.parse(fs.readFileSync('archived.json').toString())

// msgs.length = 50

const getMessage = async (channel, timestamp) => {
  return await (await fetch("https://cppftw.slack.com/api/messages.list?!!!", {
    "headers": HEADERS,
    "referrerPolicy": "no-referrer",
    "body": `------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"token\"

!!!
------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"message_ids\"

[{\"channel\":\"${channel}\",\"timestamps\":[\"${timestamp}\"]}]
------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"org_wide_aware\"

true
------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"_x_reason\"

messages-ufm
------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"_x_mode\"

online
------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"_x_sonic\"

true
------WebKitFormBoundaryuCFwDhhrnEFlx8a8
Content-Disposition: form-data; name=\"_x_app_name\"

client
------WebKitFormBoundaryuCFwDhhrnEFlx8a8--
`,
    "method": "POST"
  })).json()
}

let count = 0

msgs.forEach(async (msg) => {
  if (msg['item_type'] === 'message') {
    const filename = `${msg['item_id']}---${msg['ts']}.json`
    if (fs.existsSync(filename)) {
      d(`- skipping ${filename}`)
    } else {
      const resp = await getMessage(msg['item_id'], msg['ts'])

      if (!resp['ok']) {
        d(`error for ${filename}`, resp)
        throw "resp not ok"
      } else {
        fs.writeFileSync(filename, JSON.stringify(resp, null, 2))
        count += 1
        d({count, filename})
        execSync('sleep 1')
      }
    }
  }
})

d({count})