Make a Slack emoji from a local image

Turn a picture you already have into a small static PNG. The image is decoded and resized in this browser, with no upload or account connection. Preview the result, download it, and decide yourself whether to add it to a Slack workspace.

Try the tool

No signup. Tool inputs stay in this page’s memory. No uploads, saved history, or account connection.

Choose a local image

PNG, JPEG or WebP; up to 8 MiB. Maximum 8192 pixels per side and 16 megapixels. Export is a static PNG, at most 128 × 128 pixels and 128 KB (128,000 bytes).

The whole image is fitted without cropping or enlargement. Transparency is preserved where present. Add the downloaded file to Slack yourself if your workspace permits custom emoji.

Ready. Everything you enter in this tool stays local.

How to use it

Choose an image Use Choose a local image to select a PNG, JPEG, or WebP file up to 8 MiB. File contents must match the selected type. Images with invalid data or excessive dimensions receive an error instead of a download.
Check the preview The tool fits the entire picture within 128 by 128 pixels without cropping or enlarging it. Check that the subject is recognizable at this small size. Existing transparency is retained, but backgrounds are not removed.
Download, then add manually Select Download PNG. In Slack’s desktop emoji menu, choose Add Emoji, then Upload Image. Give the image an appropriate name and save it if your workspace allows you to add emoji.

What gets exported

The export is a static PNG no larger than 128 pixels on either side and 128,000 bytes. Those are this tool’s conservative output bounds. Slack recommends small square images under 128KB with transparency; its current help page does not describe 128 pixels as a universal hard limit.

Non-square pictures retain their proportions. Animated input, where the browser decodes it, becomes a static image; animation is not preserved. Start with a simple subject and a clean background rather than expecting tiny text to remain legible.

Clearing your work

Clear image removes the selection, preview, and download from this tool. Choosing another file also discards the previous result. The widget releases its temporary image URLs and clears the drawing surface when it is reset or left. A file you already downloaded remains wherever your browser saved it.

What this tool can and cannot do

Accepts PNG, JPEG, and WebP only; no SVG, GIF input, remote URL fetch, animation editor, or background removal.
Maximum decoded dimensions: 8192 pixels per side and 16,000,000 pixels total. Workspace permissions can prevent adding custom emoji.

FAQ

Does the original image leave my device?

The tool reads the selected file locally and makes no upload request. Adding the exported file to Slack later is your separate action.

Why was a small file rejected?

Compressed byte size and decoded dimensions are different limits. Corrupt files or images with too many decoded pixels are rejected.

Can I use any image I find?

Choose an image you have permission to use and that fits your workspace’s rules. This converter does not grant usage rights.

Sources

Slack: Add custom emoji · Checked 2026-10-28
MDN: Canvas PNG export · Checked 2026-10-28
MDN: Release object URLs · Checked 2026-10-28

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Last updated: October 28, 2026