Comparing Sierra AI and Voiceflow? Both are AI Agents & Chatbots and Voice & Phone AI tools in the directory, which is why buyers put them on the same shortlist. Below is a side-by-side look at how they price, what they integrate with, and when each is the better fit, so you can pick on the facts rather than either vendor's own sales page.
| Attribute | Sierra AI | Voiceflow |
|---|---|---|
| Pricing | Per resolution · Custom | Freemium · Free; $60/mo |
| Founded | 2023 | 2019 |
| Categories | AI Agents & Chatbots Enterprise Voice & Phone AI | AI Agents & Chatbots Voice & Phone AI |
| Integrations | Salesforce Zendesk Shopify Twilio Stripe Snowflake | Zendesk Salesforce Twilio HubSpot Shopify Airtable Google Sheets Gmail |
Sierra builds conversational AI agents for the enterprise, and it arrived with about as much star power as a startup can carry. It was founded in 2023 by Bret Taylor and Clay Bavor, and if those names ring a bell it is because Taylor co-created Google Maps, served as CTO of Facebook and co-CEO of Salesforce, and currently chairs the board of OpenAI, while Bavor spent eighteen years at Google leading its virtual and augmented reality work. Company lore says the whole thing was hatched over a grilled branzino lunch in Palo Alto.
The product lives up to the pedigree. From a single build, Sierra deploys a branded agent across chat, voice, email, SMS, and even ChatGPT, following your policies, adopting your brand's voice, and escalating gracefully when a conversation gets thorny. Its voice agents are a standout: they hold natural, low-latency conversations, read sentiment, and can even take a credit card or ACH payment over the phone in one uninterrupted call, with no clumsy handoff to a separate system.
Under the hood sits Agent OS, a platform for building, testing, and supervising agents, with tooling to run voice simulations and rehearse behavior before anything reaches a real customer. Pricing is outcome-based, tied to conversations or successful resolutions and wrapped in multi-year enterprise contracts, so Sierra is aimed at large brands rather than weekend experimenters. Reported customers include SoFi, Ramp, and Brex, and the company says its agents already serve a meaningful slice of the Fortune 50.
Sierra's fundraising has kept pace with its towering ambition, vaulting the company into the rarefied tier of the most valuable AI startups in barely two years. For enterprises that want polished, on-brand agents across every channel and are willing to invest the time and budget to do it properly, Sierra is a genuine marquee choice.
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Voiceflow is a visual platform for designing, testing, and shipping AI agents across chat and voice. Teams build conversation logic on a collaborative canvas, ground agents in knowledge bases, and deploy to web chat, phone lines via Twilio, and messaging channels. For support work specifically, native integrations let an agent create and update Zendesk tickets, touch Salesforce records, or cancel a Shopify order mid conversation, and anything else is reachable through REST APIs, custom functions, and MCP.
The company was founded in Toronto in 2019, led by CEO Braden Ream, and grew from conversation design tooling into a full agent platform. It has raised $35 million, most recently a $15 million round from OpenView in August 2023 at a $105 million valuation, following a 2021 round led by Felicis. Its own announcements cite more than 130,000 users and customers including The Home Depot, US Bank, BMW, Vodafone, State Farm, and JP Morgan.
Pricing moved to a credit system in April 2025. Third party trackers list a free starter tier, Pro from $60 monthly with 10,000 credits, Business from $150 monthly, and custom Enterprise, with extra editor seats at $50 each. Credits are consumed by every message, call, and model invocation, and reports say agents stop responding when credits run out mid cycle. Note that Voiceflow's own pricing page now steers business buyers toward a sales conversation, so treat published tiers as a floor.
Choose Voiceflow if a mixed team of designers, support leads, and developers needs to own agent behavior together, and you want one canvas covering both chat and voice. Look elsewhere if you want pure per minute phone economics (Retell, Vapi) or a fully managed enterprise deployment; and budget carefully, since seats plus credits add up faster than the sticker price suggests.
Read the full Voiceflow listing → · See Voiceflow alternatives →
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