# My last 38 cover letters all said something my resume didn't. So I built HonestFit. > Source: > Published: 2026-10-16 02:24:10+00:00 **Measured on the sample (October 15):** - gpt-oss-20b: 7 to 9 seconds per letter, 4 to 5 model calls, about 3,000 input tokens and 800 output tokens. That is **under $0.001 per letter** at Workers AI list price. - Every gpt-oss letter admitted the Kubernetes gap. - Some runs end with one flagged claim. The page shows it as a warning instead of hiding it. - Llama 4 Scout took about 30 seconds and left more issues, so gpt-oss is the default. **Known limit:** the checker knows technologies, numbers and role words. Adjectives still get through: one draft called a service "high-availability", and the resume never says that. ## Why Does Open Innovation Matter? - **The price makes the side hustle work.** Under a tenth of a cent per letter means $4 a month can cover heavy use with almost all of it as margin. At typical closed frontier-model prices, the same run with retries costs roughly 10 to 20 times more per letter. - **I can swap models per step.** Reading and searching use gpt-oss. When it returns an empty draft, Llama 4 Scout writes it. That fallback is one line of code, because both are open-weight models behind the same interface. - **The model is not the judge.** Open weights let me choose small, cheap models on purpose and put the trust in code I can read and test. With a closed API I'd be paying more to trust the model more, which is the opposite of what this tool needs. - **Your resume could stay on your machine.** The same weights run locally. I haven't built that mode yet (my 2019 Intel laptop can't run gpt-oss-20b at a usable speed), so for now the page sends your text only for the length of one request and stores nothing. ## My First User Me. I'm a full-stack developer in Korea. I write English through AI translation, and I apply to remote jobs where I can work in writing. Before I built this, I had sent 38 cover letters. I ran HonestFit's checker over all 38 against my own resume: - **38 of 38** said "13 years". My resume says "12 years 8 months". - **27** quoted numbers from side projects, like "90 of 94 MCP servers scanned" or "13 marketplace extensions", that don't appear anywhere on my resume. - **3** named a technology my resume never mentions. None of it was a lie. But a recruiter holding both pages sees two slightly different people, and I had no idea until the checker showed me. Then I ran the full workflow with my real resume against a real Senior Backend posting from my job search (its requirements list). The first run marked "SQL and NoSQL databases" as missing and wrote that I had no database experience, which is wrong (that bug is in the table above). After the fix: 5 covered, 2 partly, 1 missing (working across time zones), one draft, 6.9 seconds, $0.0008. Did I pay? I'm the user, so no. But I would. ## Prize Categories - **Best Use of Mastra** : the whole thing is a Mastra workflow with three agents and a tool, running on Cloudflare Workers. *Code and English text were produced by an AI coding agent (Claude Code) working under my direction. The resume data, the 38 letters and the decision to publish are mine. I write in Korean.*