Aider vs Gemini CLIUpdated 2026-03-16

SUMMARY

Aider (CLI) uses markdown configuration while Gemini CLI (CLI) uses markdown. They differ on 3 of 11 compared features. Both tools provide AI-assisted development but take different approaches to project configuration.

FEATURE COMPARISON

FeatureAiderGemini CLI
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

PurposeAiderGemini CLI
Settings / configuration.aider.conf.yml.gemini/settings.json
Project instructionsCONVENTIONS.mdGEMINI.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

Gemini CLI
GEMINI.md
markdown
# Project Context

## Stack
- Node.js 22 with TypeScript 5.x
- Express.js for the API server
- Prisma ORM with PostgreSQL
- React 19 with Vite for the frontend

## Architecture
- Monorepo with pnpm workspaces
- packages/api — Express REST API
- packages/web — React SPA
- packages/shared — Shared types and utilities

## Commands
- pnpm dev — Start all services
- pnpm test — Run vitest across all packages
- pnpm lint — ESLint + Prettier check
- pnpm db:migrate — Run Prisma migrations

## Conventions
- Use barrel exports (index.ts) for public APIs
- Error responses use RFC 7807 Problem Details format
- All API endpoints require authentication except /health

KEY DIFFERENCES

1. Hierarchy support

Aider: Not supported. Gemini CLI: Supported.

2. Subdirectory scoping

Aider: Supported. Gemini CLI: Not supported.

3. Ignore file

Aider: .aiderignore. Gemini CLI: 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 Gemini CLI, configure GEMINI.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

File references:
agentconfig.ing2026-03-16COMPARE(1)