Side-by-side comparison · Coding & Dev Tools

OpenAI Codex vs Vapi

Everything that matters when choosing between them, in one place: our rating, what each can do, what they cost, and the trade-offs.

Best overall

OpenAI Codex

4.2

From $8/mo

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Vapi

3.6

From $0.05/min hosting

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Comparing 2 tools. Add one more if you like.

At a glance

OpenAI Codex4.2

Best overallBest valueEasiest to use

Pick it if: ChatGPT subscribers who want a coding agent without paying for a second subscription.

Vapi3.6

Pick it if: Developers and voice AI agencies building custom phone or in-app voice agents.

Overview

Attribute	OpenAI Codex	Vapi
In one line	OpenAI's coding agent. Hand it a task and it works away while you do other things.	Developer platform for building voice AI agents that make and take phone calls.
Pricing model	Freemium	Paid
Starting price	$8/mo	$0.05/min hosting
Free plan	Yes	No
Works with Claude Code	No	Yes

Rating breakdown

Our scores out of 5. The higher bar in each row is highlighted.

Attribute	OpenAI Codex	Vapi
Overall rating	4.2Winner	3.6
Ease of useHow quickly someone non-technical gets value from it.	3.5	2.5
FeaturesHow completely it covers its own job, and how well the pieces fit together.	4.5	4.5
Output qualityHow good the results are before you fix them.	4.5	4.0
Value for moneyWhat you get for the price, including the free plan.	4.5	3.5
Speed & reliabilityHow fast it is and how often it falls over.	4.0	3.5

Feature comparison

A tick means it does this today. A dash means we haven't checked.

Attribute	OpenAI Codex	Vapi
Access & platform
Free plan	Yes	No
Mobile app	Yes	–
Desktop app	Yes	–
Browser extension	No	–
API access	Yes	Yes
Teams & business
Team workspace	Yes	Yes
Enterprise plan or SSO	Yes	Yes
Connects to other apps	Yes	Yes
Open source or self-hosted	Yes	No
AI abilities
Works with your files	Yes	–
Understands images	Yes	–
Makes images	No	No
Makes video	No	No
Writes code	Yes	No
Runs agents or automations	Yes	Yes
Learns your brand or style	Yes	–
Works in many languages	Yes	Yes
Capabilities score	14/ 17	6/ 17

Pricing

Plans as listed on each vendor's site when we last checked. Confirm before you buy.

Attribute	OpenAI Codex	Vapi
Plans	Free Free A quick look at what it can do.	Pay as you goOur pick $0.05/min hosting, plus provider costs Developers building and testing.
	Go $8/mo Occasional light tasks.	Core $29/mo plus usage Builders and early teams going live.
	PlusOur pick $20/mo Anyone who already pays for ChatGPT.	Pro 10% of hosting fee, $999/mo minimum Teams running voice agents in production at scale.
	Pro From $100/mo Developers who hit the Plus limits.	Premier Custom Large organisations.
	Business $20/user/mo billed yearly, or $25 monthly Teams of 2 or more.
	Enterprise Custom Large organisations.
Which plan to pick	If you already have ChatGPT Plus, you have Codex: just try it. If you are choosing between this and Claude Code with no existing subscription, Plus at $20 and Claude Pro at $20 cost the same, so pick whichever chat assistant you prefer. If you outgrow Plus, Pro starts at $100 and has no five-hour limit for now. The $200 tier gives new subscribers less usage than it used to, and Ultrafast mode is only on the $500 tier.	Build on pay as you go, then add Core when you go live and want email support. HIPAA compliance is a separate $2,000-a-month add-on, so check that early if you work in healthcare.

Key features

Attribute	OpenAI Codex	Vapi
Standout features	Cloud tasks Desktop app and CLI Start from your phone Automatic code review AGENTS.md Open source CLI	Bring your own providers Phone and web Tools and actions Workflows Testing and monitoring Developer tools

Pros and cons

Attribute	OpenAI Codex	Vapi
Pros	Included with every ChatGPT plan, so many people already have it Cloud tasks let you start work from anywhere and come back later Strong on tough, multi-file coding jobs The CLI is open source and works with an API key	Full choice of speech, model, voice and phone providers Strong API, SDKs, CLI and MCP for developers Free to start building Large community and templates
Cons	Five-hour and weekly limits bite on Plus if you use it seriously Cloud tasks use more of your allowance than local ones It asks fewer questions than Claude Code before changing things Model names and limits change often, which makes it hard to plan costs The $200 Pro tier now gives new subscribers less usage than before	Real cost per minute is far above the $0.05 headline Needs a developer to get the most out of it Production users report slow support and breaking changes HIPAA is an expensive add-on

Who each one is for

Attribute	OpenAI Codex	Vapi
Best for	Background tasks in the cloud Starting a task from your phone Developers already on ChatGPT Plus Coding in the terminal	Custom voice agents built by developers Agencies building AI receptionists for clients Adding voice to an app or website Mixing and matching AI and voice providers
You'll find it used by	ChatGPT subscribers Developers Startup teams Solo founders	Developers Voice AI agencies Startups Product teams

Questions people ask

Which is better, OpenAI Codex or Vapi?

OpenAI Codex scores highest overall in our ratings (OpenAI Codex 4.2/5 and Vapi 3.6/5). OpenAI Codex is best for background tasks in the cloud and starting a task from your phone. Vapi is best for custom voice agents built by developers and agencies building AI receptionists for clients.

Which is cheaper, OpenAI Codex or Vapi?

OpenAI Codex: There's a free plan, and paid plans start at $8/mo. Vapi: There's no free plan. Paid plans start at $0.05/min hosting.

Which is easier to use, OpenAI Codex or Vapi?

OpenAI Codex rates highest for ease of use in our scores. ChatGPT subscribers who want a coding agent without paying for a second subscription.

Ratings are our own, from using each tool, across ease of use, features, output quality, value for money, speed & reliability.

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