AI agents for developer: 81 real examples

A live blog aggregator pulling posts from Dev.to, AWS Community Builders, Bravo LT and RedMonk, built and deployed in a single day.

Within one night Devin produced a working unanswered-emails interface using the Gmail API, after the author wrote the authentication code themselves.

The app went live on a custom domain, dashdiary.co.uk, for a total build cost of $35.82 plus a few dollars for the domain.

The author shipped a working summariser targeting a cut from 2-3 weekly hours of newsletter reading to 30 minutes.

Small scoped fixes took about five minutes to test and merge versus roughly an hour by hand; the full-stack task failed and was rewritten.

After 2-3 review rounds the PR was production-ready and merged. The task took about 1 hour versus roughly 15 minutes coding it alone.

Cursor drafted an article on their reading trends in their style, citing Kindle highlights from the vault. The author edited it by hand.

The extension was accepted and published on the Chrome Web Store, and the author says it solves their own habit of looking down at notes.

Provisioning worked after two fixes. The MCP hid the real errors, so apply ran through Cursor's Run tool, which suggested the fix.

A roughly 3,000-line open-source Canvas tool built in four months. It cut a 45-minute weekly student check to a 2-minute conversation with Claude.

Devin found nearly every old term in a docs-wide rename, but the edits still needed 20+ manual commits.

The agent finished the page in about 5 minutes; the author reviewed the PR, tested locally, and merged it to production.

The audit found noindex, nofollow meta tags and a blocking robots.txt that hid the site from search engines, plus duplicate H1 tags.

One prompt produced the thumbnail section with accurate colours, layout and button hover states, and it beat the earlier Lovable attempt built from static images.

A production micro-SaaS went live in about 3 hours, versus an estimated 3 to 4 weeks solo.

A working, deployed app that shows images, weather, and news for a city, finished in roughly 90 minutes from an empty repo.

The author migrated 10+ Lambda functions from Node.js 14 to 20 in one pass and fixed a broken docker-compose file by auto-retrying until clean.

It located all three bugs in one shot each, the Verify bug within minutes, saving the author hours of debugging.

The author shipped 120 models, an MCP server for Claude Desktop, and 140 chaos tests with a 100% pass rate over 22 months.

About 3 hours and roughly $22 produced a live, searchable map of funded companies, versus an estimated 4 to 5 hours by hand.

After the author added the suggested indexes, page load performance improved significantly in production.

Comet generated multiple test payloads for different cases and produced a final report after the full test run.

The agents wrote over 1 million lines of code across 1,000 files, and a three-week Solid to React migration reached +266K/-193K edits.

The build took about five hours in one evening and produced 627 passing tests. The author estimates the API cost at roughly $35.

Across nearly 2,000 sessions and about $20,000 in API costs, the agents produced a 100,000-line compiler that builds Linux 6.9 on x86, ARM, and RISC-V.

The author debugged a custom WhatsApp integration hands-free while brushing their teeth, using the voice stack running locally on an M4 Pro.

Four features finished in about 2 hours instead of 3-5 days each, and the daily view took 40 minutes.

367 posts and 5 pages were migrated to MDX in one afternoon, about 4 hours, versus an estimated 3-5 days by hand.

Cognition merged 659 Devin PRs into its own codebase in one week, up from 154 in its best week of 2025.

The author ran 4 to 8 agents in parallel and wrote 300+ feature specs in one project, then ported the system to new repos.

Cognition merged 659 Devin-authored PRs into its own codebase in one week, up from 154 in its best week of 2025.

The agent rebuilt readable Go source from the stripped binary, but got some route paths wrong, such as /my-messages instead of /me/messages.

Notion now tracks 18 agents and 78 logged runs; separately, an unsubscribe agent cleared 47 vendor mailing lists in two weeks.

Four months in, the agent remembers over 470 people and 51 agents across 13 platforms, and collaborated on an open source project unnoticed.

On a dashboard filter task, Claude fixed URL query param handling in three iterations without the author touching the browser.

A dashboard and chatbot that merge tasks from calendar, mail, Linear, GitHub, Slack and meeting notes into one scored, prioritized view the author uses daily.

All the author's old utilities, such as picture converters and sprite extractors, now compile and run in DOSBox. The main game does not compile yet.

Time to diagnose a CI failure fell from 45 minutes to 6, and test flakiness dropped from 8% to 0.8%.

It found multiple remotely exploitable kernel bugs, including an NFS heap overflow undiscovered for 23 years. Five fixes or reports are linked in the post.

The author says weekly admin dropped from about 9 hours to a short morning review on Telegram, with setup taking 47 minutes.

The author consolidated 4 legacy repos into 2, moved MySQL to PostgreSQL, upgraded the full stack, and wrote full test suites, solo.

Devin built a three-endpoint Express API in about 4 minutes, but chose the wrong pagination style on a real codebase and needed review and refactoring.

A legacy pipeline with a roughly 40% pass rate lost 20 minutes of runtime and gained 35% pass rate in weeks.

The author designed, printed, and assembled a working four-servo arm in about 30 hours with almost no CAD experience, then added voice and vision control.

Combined lint and typecheck time fell from 29.04s to 1.25s, about 23 times faster, with no memory config needed for typechecking.

About 12 hours produced 46 commits and over 14,000 lines of code across three shipped products.

The author shipped a live book-sharing app and its demo video, both made with Replit Agent, during a 24-hour buildathon.

Test runs approved per day on Devin more than doubled in a couple of months, and engineers run 10 to 20 Devins in parallel.

The author cut time on literature triage and experiment setup, and says related-work sections now need less citation double-checking. No numbers are given.

The agent went from spec to live listing in under a week and has settled 20+ real on-chain transactions across four paid services.