Slack Webhook Sender

Slack's webhook endpoint does not allow the JSON requests browsers send with a CORS check first, which is why many web tools say browser sending is impossible. Slack also accepts the same payload as a form field named payload, and browsers send forms without that check, so this tool uses the form version. The catch is that Slack does not let the browser read its reply, so look in the channel to confirm the message arrived.

Open api.slack.com/apps and create (or open) an app for your workspace, choose Incoming Webhooks, toggle it on, then click Add New Webhook to Workspace and pick a channel. Slack gives you a URL that starts with https://hooks.slack.com/services/ followed by three path segments. Paste that URL into the field above.

It is the exact request Slack expects: a POST to your webhook URL with a Content-type of application/json and your payload as the body. The curl variant works in bash-style shells (macOS, Linux, Git Bash, or WSL); it will not run as-is in cmd or Windows PowerShell 5, which quote arguments differently, so switch to the PowerShell variant there instead. Either one is the reliable path because it runs outside the browser.

Yes. Open the advanced raw JSON box and paste any valid Slack payload, for example an object with a "blocks" array from the Block Kit Builder, or fields like "username" and "icon_emoji". When the raw box has content it overrides the simple message text, and the tool re-serializes it so the JSON stays valid.

It is completely free with no login. Everything runs in your browser: the payload and curl command are built locally and nothing is sent to Digital Den. The only request that ever leaves is the send itself, which goes straight from your browser to Slack. Still, treat a webhook URL like a password, since anyone with it can post to that channel.