websites used: color picker, text colorizer, text replacement

step #1: pick your colors (optional) when making gradient text for a caption, i usually use an image color picker to get exact hex codes! this just helps me match everything even better than i could when manually inputting colors! (this is completely optional, but i like doing it, so i thought i'd include it here!)

step #2: making your gradient now the fun begins! open the text colorizer linked above, and enter the text you want to be a gradient into the text box:

(all caps is by no means necessary! i'm just doing it to make the gradient stand out even more, since i'm going to have a decent amount of text in my caption.) after entering your text, choose the type of color effect you want using this drop-down menu! color effect is essentially the type of gradient/how many colors it uses, etc. play around with this to find the one you like best!

i'm sticking with horizontal gradient, but you can choose whichever one you like! (there's also a solid color option if you want to just use a color that isn't available in the tumblr text options.) after color effect, you can choose your colors using this section - if you did use the color picker from step one, you can just paste the hex codes into the boxes.

if not, click on the colored bars, and this hue picker will pop up:

drag your mouse around in the left box to choose your color. the bar on the right can be used to modify shade.

(these are the colors i'm using)

skip over the "additional text settings" section (these options mess with the html code and cause issues when you try to use it on tumblr) and check the preview to make sure you like how your gradient looks.

if you're having a bit of trouble seeing the gradient properly, you can scroll back up to "additional text settings" and turn on bold to see it better. just make sure you turn it back off before copying your code.

now you're ready to copy your code!

after making sure any additional text settings are returned to their default/unchecked states, scroll down and copy the HTML code (NOT the BBcode). select the text and copy it using command/ctrl + C or right click and click "copy".

step #3: replacing

the text colorizer used here is great, but it does add unneeded semicolons to the html code that mess with tumblr's settings and cause formatting problems.

open the text replacement site (linked at top), and paste the code you copied into the text box:

in the "replace this:" box, type ; (leave the "with this:" box blank)

click "replace text". skim over the new code to make sure the semicolons are gone (sometimes you've got to click "replace text" a couple of times for it to work), and then either click "copy to clipboard" or select and copy the text manually.

step #4: writing your caption now that you've got your code, open tumblr and make a new photo post. look in the top right-hand corner of your screen, and make sure "legacy editor" is turned on. if it isn't, click the toggle to turn it on.

next, you need to make sure your text editor is set to html. to do this, click the little gear in the top right corner of the new post. select "html" from the drop-down menu next to "text editor", and then close the settings. [07.27.23 update: if, like me, you're stuck using the new editor, you can still set your post type to html, and gradient text will still work. the post editor will just turn your files into code when you're editing, and you'll have to fix the spacing in between your gifs (if you're using this for a gifset caption) in the preview tab. it looks super weird and alarming at first, but it does still work with the new post editor.]

upload your gifs and then move down to the caption. open the html tab and then paste your code! once you've done that, click on the preview tab to check how it looks.

my gradient looks pretty good, but i'm going to bold the text to make it more visible. here's how to use html to do that:

<strong>code goes here</strong>

here is a list of other html codes you can use to stylize your text! (they use <;b> for bold text, this is another way to do it, either method works fine!)

if you want to have another line of text under/above your code you need to add <br> at the end of the top line to create a line break (just pressing enter won't work). here's an example of how to format that:

text text text<br> text text text&lt;br> text text text

write the rest of your caption, and then you're done! here's my end result and my final code: