Aider vs Windsurf
AI Agent Reliability Comparison
According to StupidLLM's incident database of 64 documented AI agent failures, Aider has 1 incidents (avg severity 6.3/10) while Windsurf has 1 (avg severity 7.5/10). Here's how these two AI coding agents compare on reliability, failure modes, and real-world risk.
Aider
Top Failure Modes
Worst Incident
STUPID-2026-0005 6.3/10Windsurf
Top Failure Modes
Worst Incident
STUPID-2026-0007 7.5/10Comparison Summary
| Metric | Aider | Windsurf |
|---|---|---|
| Total Incidents | 1 | 1 |
| Avg Severity | 6.3/10 | 7.5/10 |
| Critical Incidents | 0 | 0 |
| Top Failure Mode | Wrong File | Ignored Instructions |
Frequently Asked Questions
Is Aider or Windsurf more reliable?
Based on StupidLLM's incident database, Aider has 1 documented failures (avg severity 6.3/10) while Windsurf has 1 (avg severity 7.5/10). Aider shows better reliability based on average severity scores.
What are the main differences between Aider and Windsurf failures?
Aider's most common failure mode is wrong file, while Windsurf most commonly fails via ignored instructions. Aider has 0 critical incidents vs Windsurf's 0.
Which has more critical-severity failures?
Both Aider and Windsurf have 0 critical-severity incidents — the most dangerous category of AI agent failure.
What is the most dangerous failure mode for Aider?
Aider's most frequent failure mode is wrong file — its worst documented incident (STUPID-2026-0005) was rated 6.3/10 severity. Understanding these failure patterns helps teams decide whether Aider is safe for their specific use case.
What is the most dangerous failure mode for Windsurf?
Windsurf's most frequent failure mode is ignored instructions — its worst documented incident (STUPID-2026-0007) was rated 7.5/10 severity. Understanding these failure patterns helps teams decide whether Windsurf is safe for their specific use case.
Should I use Aider or Windsurf for production code?
Based on StupidLLM's reliability data, Aider has a lower average failure severity (6.3/10 vs 7.5/10), making it the statistically safer choice for production environments. However, both agents have documented critical incidents — no AI coding agent is risk-free.
How many verified incidents does each agent have?
Aider has 1 verified incidents out of 1 total, while Windsurf has 1 verified out of 1. Verified incidents are confirmed against source evidence (GitHub PRs, bug reports, news articles), making them the most reliable data points in StupidLLM's database.
How does Aider compare to other AI agents?
StupidLLM tracks 27 AI coding agents. Aider has 1 documented failures — placing it in the mid-range for reliability. See the full comparison matrix for context against all tracked agents.
How does Windsurf compare to other AI agents?
StupidLLM tracks 27 AI coding agents. Windsurf has 1 documented failures — placing it among the higher-risk agents in the database. See the full comparison matrix for context against all tracked agents.