How to round an image with Glide library?

Glide V4:

    Glide.with(context)
        .load(url)
        .circleCrop()
        .into(imageView);

Glide V3:

You can use RoundedBitmapDrawable for circular images with Glide. No custom ImageView is required.

 Glide.with(context).load(url).asBitmap().centerCrop().into(new BitmapImageViewTarget(imageView) {
        @Override
        protected void setResource(Bitmap resource) {
            RoundedBitmapDrawable circularBitmapDrawable =
                    RoundedBitmapDrawableFactory.create(context.getResources(), resource);
            circularBitmapDrawable.setCircular(true);
            imageView.setImageDrawable(circularBitmapDrawable);
        }
    });

Check this post, glide vs picasso...
Edit: the linked post doesn't call out an important difference in the libraries. Glide does the recycling automatically. See TWiStErRob's comment for more.

Glide.with(this).load(URL).transform(new CircleTransform(context)).into(imageView);

public static class CircleTransform extends BitmapTransformation {
    public CircleTransform(Context context) {
        super(context);
    }

    @Override protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) {
        return circleCrop(pool, toTransform);
    }

    private static Bitmap circleCrop(BitmapPool pool, Bitmap source) {
        if (source == null) return null;

        int size = Math.min(source.getWidth(), source.getHeight());
        int x = (source.getWidth() - size) / 2;
        int y = (source.getHeight() - size) / 2;

        // TODO this could be acquired from the pool too
        Bitmap squared = Bitmap.createBitmap(source, x, y, size, size);

        Bitmap result = pool.get(size, size, Bitmap.Config.ARGB_8888);
        if (result == null) {
            result = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
        }

        Canvas canvas = new Canvas(result);
        Paint paint = new Paint();
        paint.setShader(new BitmapShader(squared, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP));
        paint.setAntiAlias(true);
        float r = size / 2f;
        canvas.drawCircle(r, r, r, paint);
        return result;
    }

    @Override public String getId() {
        return getClass().getName();
    }
}