Chatbots · Head-to-head

ChatGPT vs Sierra

ChatGPT (freemium, AI Score 9.3/10) vs Sierra (paid, AI Score 8.5/10). Side-by-side pricing, features, pros and cons, and which to pick.

The verdict

Pick ChatGPT if…

Try ChatGPT →

Pick Sierra if…

→your primary use case is enterprise support leaders at companies with high ticket volume and real backend systems (billing, orders, accounts) who want agents that complete transactions across voice and chat, and who can fund a multi-quarter integration.
→you need: support

Try Sierra →

Spec	ChatGPT	Sierra
Category	Chatbots	Chatbots
Pricing model	freemium	paid
Headline pricing	Free + Go (low-cost, regional) + Plus $20/mo + Pro $200/mo; Business and Enterprise above	Enterprise only — outcome-based, contact sales
Free tier	Yes — the free plan now defaults to current-generation GPT-5.6 Luna with the Think button, image generation, browsing and Codex mobile access, under usage caps OpenAI does not publish	—
AI Score	9.3/10	8.5/10
Best for	Generalists and small teams who want one $20 subscription covering reasoning, full-duplex voice, image and video generation, Deep Research and a phone-controllable coding agent instead of stitching four separate tools together.	Enterprise support leaders at companies with high ticket volume and real backend systems (billing, orders, accounts) who want agents that complete transactions across voice and chat, and who can fund a multi-quarter integration.
Editor's pick	✓ Yes	—
Use cases	productivity agents content-creation research	support agents
Date added	2025-03-01	2026-06-27

Chatbots · freemium

✓Free tier runs a current-generation model (GPT-5.6 Luna) with the Think button, not a downgraded legacy one
✓Reasoning-effort slider on Plus and Pro puts per-message thinking depth under your control instead of a hidden router's
✓Codex mobile lets you start, steer and approve coding agent runs from your phone — and it is on every plan, including Free
✓Broadest single-app surface: full-duplex GPT-Live voice, native image generation, inline Runway video, Deep Research, agent mode and file analysis
✓Lockdown Mode is a real architectural cutoff against prompt-injection exfiltration, not a policy promise

×OpenAI's headline figures — 68% fewer factual errors, Sol's Terminal-Bench result — are self-measured on evaluation sets the company has not published
×Not the leader on any single axis anymore: Claude is better for long-form writing and agentic coding, Gemini 3.5 Pro for ecosystem reach and context length
×The most interesting features land on the $200/mo Pro tier first — the finance mode shipped Pro-only and stayed there
×Video generation leans on a Runway partnership rather than a deeply integrated Sora, and Go-tier price and availability differ by country

Chatbots · paid

✓One agent definition serves chat, voice, SMS, WhatsApp and email with consistent behaviour and the same backend actions
✓Agents execute real transactions — refunds, subscription changes, rebookings — through connected systems, not just retrieval answers
✓Simulation-based testing and the Agent Data Platform give unusually strong pre-deploy evaluation and post-deploy auditing for this category
✓Model-agnostic routing across multiple frontier providers, so a single vendor's outage or price change doesn't strand the deployment
✓Outcome-based billing means an agent that fails to resolve doesn't generate a charge

×No public pricing, no free tier and no self-serve signup — you cannot evaluate it without a sales process
×Per-resolution billing is unforecastable, and the contractual definition of a "resolution" is where the real cost risk sits
×The 2026 field is crowded — Decagon, Salesforce Agentforce, Intercom Fin and Zendesk's agents all take backend actions now, so action-taking alone is no longer a differentiator
×Deep backend integration is where the value lives, which means a multi-quarter implementation and real engineering effort, not a widget you embed

Updated 2026-08-10. Spec data sourced from official product pages and tracked in our public directory at /tools.