I'd recommend git-spice, it's very easy to use and powerful, and of course open-source. I've tried graphite but found that they made it too convoluted for what it is.
I will second git-spice. It does exactly what you want and, importantly, no more than that. There's no upsell to anything else; it's "just" a good tool that knows its purpose and boundaries.
I will second git-spice. It does exactly what you want and, importantly, no more than that. There's no upsell to anything else; it's "just" a good tool that knows its purpose and boundaries.