Aider vs OpenCodeUpdated 2026-03-16

SUMMARY

Aider (CLI) uses markdown configuration while OpenCode (CLI) uses markdown. They differ on 2 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.

FEATURE COMPARISON

FeatureAiderOpenCode
Config formatmarkdownmarkdown
Hierarchy support
Global config
Project config
Subdirectory scoping
File inclusion / imports
Ignore file.aiderignore
IDE integrationCLICLI
Schema / structureFree-form (Markdown)Free-form (Markdown)
Git committed
EncodingUTF-8UTF-8

FILE MAPPING

PurposeAiderOpenCode
Settings / configuration.aider.conf.ymlopencode.json
Project instructionsCONVENTIONS.mdAGENTS.md

SIDE-BY-SIDE CODE SAMPLES

Aider
CONVENTIONS.md
markdown
# Project Conventions

## Language
- TypeScript strict mode, no `any` types
- Prefer const over let, never use var
- Use template literals over string concatenation

## Architecture
- Feature-based folder structure under src/features/
- Each feature exports through an index.ts barrel file
- Shared utilities go in src/lib/

## Error Handling
- Use Result<T, E> pattern for expected failures
- Throw only for programmer errors
- Always log errors with structured context

## Testing
- Colocate tests next to source files (*.test.ts)
- Use factories for test data, not fixtures
- Integration tests in __tests__/ directories

OpenCode
AGENTS.md
markdown
# Project Instructions

## Overview
This is a TypeScript monorepo using pnpm workspaces.

## Code Style
- Use strict TypeScript with no implicit any
- Prefer functional components with hooks
- All exports should be named (no default exports)

## Architecture
- /packages/core — shared business logic
- /packages/ui — React component library
- /apps/web — Next.js frontend

## Build & Test
Run tests with: pnpm test
Build all packages: pnpm build
All PRs must have >80% coverage on changed files.

## Conventions
- Use conventional commits (feat:, fix:, chore:)
- Prefer composition over inheritance
- See @docs/api-guidelines.md for API design patterns

KEY DIFFERENCES

1. Hierarchy support

Aider: Not supported. OpenCode: Supported.

2. Ignore file

Aider: .aiderignore. OpenCode: Not supported.

WHICH SHOULD I USE?

Recommendation

Choose based on your IDE/CLI preference. If you use Aider, configure .aider.conf.yml. If you use OpenCode, configure AGENTS.md. Many projects include config files for multiple tools so each team member can use their preferred editor.

PORTABILITY TIP

sync-instructions.sh
bash
# Maintain a single source of truth:
cp AI-INSTRUCTIONS.md CLAUDE.md
cp AI-INSTRUCTIONS.md .cursorrules
cp AI-INSTRUCTIONS.md AGENTS.md

SEE ALSO

agentconfig.ing2026-03-16COMPARE(1)