Deletes slack public/private channel and chat messages.

delete-slack-messages.js

#!/usr/bin/env node

// Channel ID is on the the browser URL.: https://mycompany.slack.com/messages/MYCHANNELID/
// Pass it as a parameter: node ./delete-slack-messages.js CHANNEL_ID

// CONFIGURATION #######################################################################################################

const token = 'SLACK TOKEN'; // You can learn it from: https://api.slack.com/custom-integrations/legacy-tokens 

// GLOBALS #############################################################################################################

let channel = '';

if (process.argv[0].indexOf('node') !== -1 && process.argv.length > 2) {
    channel = process.argv[2];
} else if (process.argv[0].indexOf('delete') !== -1 && process.argv.length > 1) {
    channel = process.argv[1];
} else {
    console.log('Usage: node ./delete-slack-messages.js CHANNEL_ID');
    process.exit(1);
}

const https         = require('https');
const baseApiUrl    = 'https://slack.com/api/';
const messages      = [];
const historyApiUrl = baseApiUrl + 'conversations.history?token=' + token + '&count=1000&channel=' + channel + '&cursor=';
const deleteApiUrl  = baseApiUrl + 'chat.delete?token=' + token + '&channel=' + channel + '&ts='
let   delay         = 300; // Delay between delete operations in milliseconds
let   nextCursor    = '';

// ---------------------------------------------------------------------------------------------------------------------

function deleteMessage() {

    if (messages.length == 0) {

        if (nextCursor) {
            processHistory();
        }

        return;
    }

    const ts = messages.shift();

    https.get(deleteApiUrl + ts, function (res) {

        let body = '';

        res.on('data', function (chunk) {
            body += chunk;
        });

        res.on('end', function(){
            const response = JSON.parse(body);

            if (response.ok === true) {
                console.log(ts + ' deleted!');
            } else if (response.ok === false) {
                console.log(ts + ' could not be deleted! (' + response.error + ')');

                if (response.error === 'ratelimited') {
                    delay += 100; // If rate limited error caught then we need to increase delay.
                    messages.push(ts);
                }
            }

            setTimeout(deleteMessage, delay);
        });
    }).on('error', function (e) {
        console.error("Got an error: ", e);
    });
}

// ---------------------------------------------------------------------------------------------------------------------

function processHistory() {

    https.get(historyApiUrl + nextCursor, function(res) {

        let body = '';
    
        res.on('data', function (chunk) {
            body += chunk;
        });
    
        res.on('end', function () {

            nextCursor = null;
    
            const response = JSON.parse(body);

            if (response.messages && response.messages.length > 0) {

                if (response.has_more) {
                    nextCursor = response.response_metadata.next_cursor;
                }

                for (let i = 0; i < response.messages.length; i++) {
                    messages.push(response.messages[i].ts);
                }
        
                deleteMessage();
            }
        });
    }).on('error', function (e) {
          console.error("Got an error: ", e);
    });
}

// ---------------------------------------------------------------------------------------------------------------------

processHistory();

Nice code

would it be possible to remove DMs, too?

Code deletes the messages but when I come back they are there again. Any ideas?

Thank you so much!! Exactly what i needed.

I modified the code a bit to delete direct messages and continue deleting after 1000 limit. If anyone is interested:
https://gist.github.com/gummi-io/f3dbfebfcd5fd1fc4e42da1c0e2b41c8 ;)

thanks man. works like a charm

Hi there! I'm a bit of a noob when it comes to APIs and in need of a bit of help..

Do I understand correctly that in order to wipe my message history in my #general, I: 1) modify the raw code; 2) DL it as a .zip file; 3) import it to my Slack?

If so, what are the fields I need to modify in the raw code and how can I find my #general channel ID?

TY

Hi @niiongi, follow this post: https://medium.com/@jjerryhan/cleaning-all-messages-on-slack-channel-c46d71615c9a

@woodyb23 (and others) Slack imposes an API request limit of 1 per second (https://api.slack.com/docs/rate-limits#web). Short bursts are allowed, but once you hit 20 messages or so, requests will start getting rejected. Modify the settings of this script to use a delay of say 1250ms so you won't hit the rate limit and messages will be deleted properly.

Thank you very much~!

I modified the code a bit, also added promise methods, delete all messages, and delete direct message. :)
https://github.com/yunabsd/SlackRemoveMe

Having issues when using it for 1-on-1 Chat, can't get around this:

/Users/name/Scripts/delete-channel-messages.js:66
        for (var i = 0; i < response.messages.length; i++) {
                                              ^

TypeError: Cannot read property 'length' of undefined
    at IncomingMessage.<anonymous> (/Users/name/Scripts/delete-channel-messages.js:66:47)
    at IncomingMessage.emit (events.js:187:15)
    at endReadableNT (_stream_readable.js:1091:14)
    at process._tickCallback (internal/process/next_tick.js:174:19)

BUMP**

Can't figure out why but it seems cannot delete chats, just general group chats.

EDIT:
Just read that the feature doesn't exist to delete private messages via api anymore, they allow you to delete view archive and that's only available on the paid plan.

Basically, they are forcing you to pay.

Now, It supports chat messages as well. And automatically proceed to the next 1000 messages.

Not working

super neat ! thank you !

Works perfectly!

Thank you for sharing. I had a dream where hubot had this functionality in coffee script!
/hubot cleanup --start=2017-1-1 --end=2018-1-1 (admins permissions only)

KUDOS!