What Replit Agent Actually Does
Replit Agent launched in September 2024 as an AI that builds complete web apps from your description.
You tell it "build me a Twitter clone" and it actually attempts to do it
- database, authentication, frontend, the works.
Here's what makes it different from GitHub Copilot or other coding assistants: it doesn't just complete your code, it writes entire applications from scratch.
Think of it as hiring a developer who never asks questions and makes confident mistakes.
The Reality Check
I've built maybe 10-12 apps with Agent since it launched. Here's the reality:
The Good Shit:
Agent genuinely builds working applications fast. I threw "create a expense tracker with charts" at it and got a functional app in 15 minutes. The database schema was reasonable, React components worked, even had basic auth.
For MVPs and prototypes, it's legitimately impressive.
Where It Shits the Bed:
Complex business logic breaks Agent's brain every time. Asked it to build a scheduling app with timezone handling
- it generated beautiful code that scheduled meetings at 3am and double-booked everyone.
Spent 6 hours debugging race conditions it confidently created while I cursed at my screen.
Database Relationships Are a Coin Flip:
Sometimes it creates perfect normalized schemas with proper foreign keys.
Other times it stores JSON blobs everywhere and calls it a day.
No way to predict which you'll get.
The July 2025 Security Incident
That July database thing?
That's when I realized this tool has some serious trust issues. Agent went rogue during a user test, deleted a company's entire database, then lied about it when asked what happened. Replit's CEO had to publicly apologize.
The incident report showed Agent ignored safety protocols, created 4,000 fake users to "test" the system, then told the user everything was working fine.
This happened during a code freeze when it shouldn't have been making database changes at all.
Makes you wonder what other "confident" decisions it's making behind the scenes.
Recent Updates (September 2025)
They just launched Plan Mode which lets you discuss ideas with Agent without it immediately starting to code.
Smart move
- lets you iterate on requirements before it goes off and builds something completely wrong.
The effort-based pricing from June 2025 actually improved things.
Instead of flat $0.25 charges for everything, simple fixes now cost $0.10 while complex builds might hit $3-5. More fair, though the unpredictability annoys some users.
What It's Actually Good For
Rapid Prototyping:
Need an MVP in a day? Agent delivers. The code won't win awards but it usually works.
Learning: Great for seeing how different design patterns are implemented.
Ask it to build something, then study the code.
CRUD Apps: If your app is basically forms that save to a database, Agent handles this well.
Educational Projects:
Perfect for students learning development
- shows complete app structure and patterns.
What Breaks It
Authentication:
Every. Single. Time. The auth flow will have holes you could drive a truck through.
API Integrations:
It hardcodes API keys, ignores rate limits, and assumes every request succeeds.
Performance:
Agent has zero concept of optimization. Built me a to-do app that took 3 seconds to load 10 items. N+1 queries everywhere, no caching, jQuery included for one button click.
Complex State Management:
React apps become unmaintainable messes of prop drilling and state conflicts.
Security Vulnerabilities:
Every deployment needs a security audit
- SQL injection, XSS, hardcoded secrets are standard.
Database Design:
Sometimes creates proper schemas, other times stores everything as JSON blobs.
Error Handling:
Assumes the happy path
- no input validation, no error boundaries, crashes on edge cases.
The bottom line: Agent kicks ass for prototypes, would get you fired if deployed to production without massive cleanup.
