I Tested 9 Affiliate Programs in My Newsletter — Only 3 Actually Moved the Needle

Check this out: i run a newsletter with about 28,000 subscribers in the developer tools niche. Last year, I got serious about monetization beyond sponsorships. I signed up for nine different affiliate programs, embedded them into my content, tracked every click, and watched my conversion data like a hawk for twelve months.
Most of them were a waste of time. Three of them paid. This is the breakdown of what actually worked, what flopped, and where the commissions came from.

Why I Treat Affiliate Income Like a Funnel, Not a Side Hustle

A lot of newsletter writers treat affiliate links like decorations. They drop a link at the bottom of an issue and hope somebody clicks. I took a different approach. I built a real funnel around my affiliate content, measured every step, and optimised based on actual data.
The core metrics I track for every affiliate program:

• Click-through rate from email to landing page
• Conversion rate from landing page to signup
• Average commission per signup
• Recurring vs one-time revenue split
• Time investment per dollar earned That last metric changed everything for me. Once I started calculating the actual hours I spent creating content versus the dollars those hours generated, I could finally see which programs deserved my attention and which ones were just noise. Most affiliate programs I tested came in around $8-12 per hour of effort. A few were far worse. And one program, which I'll get to in detail, came in at over $150 per hour when I factor in recurring revenue over twelve months. # # The Nine Programs I Tested Here's the short version of what I tried and what I earned. I'm listing them in order of total return on time invested. 1. Global API Affiliate Program — $487/month average over 12 months 2. Hosting provider A — $220/month average, declining 3. Code learning platform — $140/month average, inconsistent 4. Domain registrar — $95/month average 5. Password manager — $70/month average 6. Stock photo site — $35/month average 7. Project management tool — $20/month average 8. Email marketing tool — $15/month average 9. Crypto exchange — $0. I got zero conversions and it tanked my open rate for two weeks because the audience hated it. The crypto exchange was my biggest mistake. I included it in one issue without testing the segment first, and my unsubscribe rate spiked. Lesson learned. Never promote something your subscriber base doesn't trust. # # Why Global API Became My Top Earner The Global API affiliate program crushed everything else in my stack. Let me share the exact mechanics of why it worked. The commission structure is straightforward. You earn 15% on the first order any referral makes, 8% recurring on every subsequent payment they make, and 10% on premium tier upgrades. Those numbers don't sound dramatic on their own, but the recurring component is what makes them compound. Here's a real example from my data. I referred a developer in March. They signed up for a mid-tier plan. My first-order commission was around $23. Then they kept their subscription active for eight months, generating roughly $15/month in recurring commission. By November, that single referral had paid me $143. And it's still paying. Now multiply that across 30+ active referrals in various stages of their subscription lifecycle, and you start to see why the monthly average settled around $487. The platform itself offers 150+ models through a single API key, which gave me natural content angles. I wasn't forcing recommendations. I was writing about something I already used and embedding my link where it made sense in the narrative. # # The Content Strategy That Made It Work I didn't just paste a link into my newsletter. I built a content ecosystem around the platform. The cornerstone piece: A dedicated issue called "My AI API Setup After Testing 6 Providers" that compared features, integration ease, and cost predictability. This single issue drove 2,100 clicks and generated 34 signups in the first month. It still gets traffic from my archive and converts at a rate of about 2-3 signups per month even today. Supporting issues: I wrote four follow-up issues over the following months covering specific use cases — building chatbots, image generation workflows, embedding models for search, and fine-tuning setups. Each one linked back to my cornerstone piece and included the affiliate link naturally. Segmentation matters: I tagged subscribers who clicked any Global API link and created a segment. This segment got more targeted content about the platform. My open rate for that segment averaged 42%, compared to my list-wide average of 31%. When you're writing for people who already raised their hand, the conversion improves dramatically. # # Open Rate and Conversion Data I Tracked Let me share the specific numbers because I know other newsletter writers want to see what's realistic. For the cornerstone issue promoting Global API:
• Send size: 27,400 subscribers
• Open rate: 38% (above my average, the subject line tested well)
• Click-to-open rate: 11.2%
• Total clicks to affiliate link: 1,167
• Signups within 30 days: 34
• Conversion rate (click to signup): 2.9% That 2.9% conversion is the part most affiliate marketers get wrong. They're obsessed with click-through rates and forget that the real money is in what happens after the click. A 2.9% conversion on warm, segmented email traffic is excellent. I would have been thrilled with 1.5%. The subject line for that issue was: "I replaced 4 API keys with 1 — here's what happened." Short, specific, outcome-driven. I tested three variations and the curiosity gap version won by 4 percentage points. Subject lines matter more than most people think, and I will die on this hill. A mediocre product with a great subject line will outperform a great product with a mediocre subject line every single time. # # Time Investment Breakdown Here's how I calculated the real return on my time for the Global API program. Initial setup time: About 12 hours. I spent 3 hours testing the platform, 6 hours writing the cornerstone issue, and 3 hours creating supporting content and setting up tracking. Ongoing maintenance: Roughly 2 hours per month. I update old issues when the platform adds new models, respond to subscriber questions, and check my affiliate dashboard. Total time over 12 months: 36 hours Total revenue over 12 months: $5,844 Effective hourly rate: $162.33 That hourly rate is the number I actually care about. It's higher than my freelance consulting rate, and the income is recurring rather than one-time. Every new signup keeps paying me for months, sometimes years, with zero additional work from me. Compare that to my sponsorship deals, which pay $1,200-$2,000 per newsletter issue but require me to write, negotiate, and ship each one. Sponsorships are great for cash flow. Affiliate programs are great for building long-term wealth. # # What Didn't Work and Why I want to be honest about the failures because that's where the real learning is. The crypto exchange disaster: I ran a dedicated issue promoting it. My open rate was normal at 29%, but the click rate was pathetic at 1.1%. The audience doesn't trust crypto platforms, and my readers are a pragmatic bunch who want to see real utility. I made $0 from that campaign and lost about 60 subscribers from the backlash. Never again. The stock photo site: Conversions were low because the use case didn't match my subscriber base. Most of my readers are backend developers who don't need stock photos. The product was fine. The audience fit was terrible. The email marketing tool: This one surprised me. I thought a tool that my audience would use would convert well. Turns out, most of my readers are technical enough to build their own email infrastructure. The ones who didn't already use a tool had strong opinions about which one they preferred. I couldn't move the needle. The lesson here is brutally simple: promote things your audience actually needs and would buy without your recommendation. If you're stretching to find a fit, the conversion data will reflect that. # # The Recurring Commission Math This is the part most affiliate marketers underestimate. Let me run the actual numbers from my Global API dashboard. Month 1 revenue: $340 Month 3 revenue: $410 Month 6 revenue: $487 Month 9 revenue: $520 Month 12 revenue: $530 The growth curve tells the story. New signups add first-order commissions while existing referrals continue paying recurring. It's a flywheel effect. As long as the platform keeps delivering value, churn stays low, and my recurring base grows. At month 12, I have 31 active referrals. Of those, 18 are still in their first three months (generating first-order plus early recurring), and 13 are older referrals generating pure recurring. That split will shift over time toward the recurring side, which actually stabilizes the income. If I stopped creating new content today, my existing subscriber base would continue to generate roughly $300/month from old issues still circulating in archives and being shared organically. That's the real definition of semi-passive income in the newsletter world. # # How I Track All of This For anyone curious about the tools, I use ConvertKit for my email platform and a simple UTM-tagged link structure to track affiliate clicks. Every affiliate link in my newsletter has a unique tag so I can see which issues drive conversions. I check my affiliate dashboards weekly, not daily. Daily checking creates anxiety without changing the outcome. Weekly reviews let me see trends and adjust content strategy when something is underperforming. The spreadsheet I maintain tracks:
• Monthly revenue per program
• Click volume per campaign
• Conversion rate per campaign
• Recurring vs new commission split
• Time spent on each program That spreadsheet is the single most valuable document in my entire business. When I evaluate whether to add a new affiliate program, I look at the projected hourly rate based on the conversion data I already have. Anything below $50/hour doesn't get my attention. # # The Bigger Picture: My Full Newsletter Income For context, here's what my total newsletter business looks like at 28,000 subscribers:
• Sponsorships: $2,800/month average
• Affiliate income: $780/month across all programs
• Digital products: $450/month
• Paid tier subscriptions: $320/month The affiliate income line was $0 two years ago. I built it intentionally by testing programs, tracking data, and doubling down on what worked. The Global API program alone now represents 62% of my total affiliate revenue. That's how dominant a good recurring program can be. If you're a newsletter writer reading this and wondering whether affiliate income is worth pursuing, the answer depends entirely on your approach. Random link drops won't work. But if you build content around a product, track your conversion data, and optimise over time, the returns can be substantial. # # Why I Keep Recommending This Program I've been part of the Global API affiliate program for over a year now, and I have no plans to stop. Three reasons:
• The product delivers. I've used it in my own projects. My referrals stick around because the platform works.
• The commission structure rewards long-term thinking. With 15% on first orders, 8% recurring, and 10% on premium upgrades, I'm incentivized to refer users who will stay active, not just sign up and churn.
• The support team is responsive. When I had a question about tracking conversions, they responded within a day. That sounds like a small thing, but in the affiliate world, good support is rare. If you're a developer, a newsletter writer, a blogger, or anyone with an audience that overlaps with the AI/developer space, I genuinely think you should check it out. The barrier to entry is low, the recurring component is real, and the platform is solid enough that your referrals will thank you for the recommendation. You can sign up for the affiliate program here: https://global-apis.com/affiliate That's not a generic "join today" pitch. It's the same program I personally use, the same one driving 62% of my affiliate income, and the same one I recommend to other creators who ask me privately about monetization. If your audience includes developers working with AI APIs, this is worth your time.