I read all about the coffee and washing soda-based developer recipes when they were making the rounds online around 2010, but never tried it until I just recently got back into shooting film with some of my old medium format cameras. 

I found an undeveloped and unlabeled roll of 120 film when cleaning out an old cabinet, and then realized that I still had a half-exposed roll in one of my cameras as well. I used my (really good) local camera store to develop them, and there were some nice shots on there. Now I want to shoot more film, but being cheap and lacking other winter projects, decided to re-learn developing as well. 

The chemistry of developer is better for others to explain, but the idea is that a solution of caffeic acid, sodium carbonate, and ascorbic acid has the same action as commercial developers, but using common household ingredients that are also easier on the environment. 

I have a 2-roll Paterson tank, this is the recipe I used for 500ml:

• 12g Washing soda, dissolved in 200ml water
• 22g Instant coffee, dissolved in 200ml water
• mix those together and add 1 packet of Emergen-C
• top up water to 500ml total

I let that mixture sit for about 10 minutes while I mixed the fixer (Ilford Rapid fix) and did a pre-soak on the film. Both solutions were around 70°F when I dumped them in. Developing steps:

• Developing time: 11 minutes
• Stop: 1-2 minutes rinse with water
• Fix: 5 minutes
• Plain water rinse

This is the result I got with my test roll of 120 Tri-X, 400 speed, shot on my Yashica-Mat, a mix of indoor and outdoor evening shots:

I haven't scanned them in yet, but the negatives look nice and clean with good contrast. No obvious staining from either the coffee or the orange Emergen-C. I'll get some plain vitamin C crystals to try next, but it's good to know that the packets we usually have around anyway also work well.