Cursor IDE vs Codex CLI: which to use with your own API key

A single Codex Key API key works in both Cursor IDE and Codex CLI. The real question is where each tool wins. The short answer: they complement each other, they don't compete.

TL;DR

Task	Tool
Surgical edits, single-file refactor	Cursor
Multi-file operations, batch jobs	Codex CLI
Reading and navigating code	Cursor
CI/CD integration, scripts, agents	Codex CLI
Exploring an unfamiliar repo	Cursor (Ask mode)
Generating a series of similar files	Codex CLI

Cursor IDE: interactivity

Strengths:

• Inline autocomplete with codex-5.3 — effectively free (×0.9)
• Cmd+K for in-place edits without leaving the buffer
• Composer: multi-file changes with diff preview
• Reads the symbol graph — the model sees project-wide context

Weaknesses:

• Closed workflow — doesn't slot into scripts
• For batch work (apply the same change to 50 files) the UI is slow and expensive
• No headless mode

Setup with Codex Key:

Settings → Models → OpenAI API Key:    ck_live_xxx
Settings → Models → OpenAI Base URL:   https://api.codexkey.ru/v1
Enable models:                          gpt-5.4, gpt-5.5, codex-5.3

Codex CLI: automation

Strengths:

• Headless: drops into Makefiles, GitHub Actions, shell scripts
• Sees git, the filesystem, can run tests
• Sessions stored locally — you can resume context
• Batch: for f in src/**/*.ts; do codex --apply "add JSDoc" "$f"; done

Weaknesses:

• No inline editor completion
• Thinner UI — no diff preview, terminal-only
• Steeper learning curve

Setup with Codex Key:

export OPENAI_API_KEY=ck_live_xxx
export OPENAI_BASE_URL=https://api.codexkey.ru/v1

codex --model gpt-5.4 "rename all callers of getUser to getUserAsync"

Real workflow: both

Teams that moved to Codex Key usually run a hybrid:

1. Cursor — primary IDE for writing code and quick edits
2. Codex CLI — for tasks like:
   • "Run this refactor across all of apps/web"
   • "Generate 12 migrations from this template"
   • "Code-review the latest PR in CI"

GitHub Actions example using Codex CLI:

- name: AI code review
  env:
    OPENAI_API_KEY: ${{ secrets.CODEX_KEY }}
    OPENAI_BASE_URL: https://api.codexkey.ru/v1
  run: |
    git diff origin/main..HEAD | \
      codex --model gpt-5.5 --no-interactive \
      "review this diff, list bugs and risks" > review.md

Pricing in both cases

Billing is identical — tokens are metered on Codex Key's side, the tool doesn't matter:

Model	Coef.	Best fit
codex-5.3	×0.9	Cursor autocomplete
gpt-5.4	×1.0	Both
gpt-5.5	×4.5	Codex CLI for batch reasoning

Cursor with codex-5.3 autocomplete enabled typically runs ~$0.40-0.70/day per active dev. Codex CLI consumption tracks request volume.

If you can only pick one

Only one tool? Take Cursor — it covers 80% of work and gives the fastest ROI on your API key.

Add Codex CLI when:

• Repetitive batch tasks appear
• You need CI/CD integration
• You want to automate review or doc generation

Bottom line

Cursor and Codex CLI are not competitors — they're two layers of one workflow. A single Codex Key API key covers both. Start with Cursor for daily work, add the CLI when batch tasks become the bottleneck.