Robylon vs Sierra (2026)

Robylon

by Robylon AI

Sierra

by Sierra

Pros

• ✓Publishes a full self-serve price ladder in both billing states, including a free forever plan and a per-plan credit allowance, with each add-on priced item by item.
• ✓Thirty-two named integrations on a dedicated directory page, spanning helpdesks, commerce, CRM, storage and voice carriers, with write access rather than read-only lookups.
• ✓Forty-nine supported languages enumerated by the vendor, and a public trust portal listing SOC 2, GDPR, CPRA and HIPAA as compliant alongside a SOC 2 Type 2 report.

Limitations

• –No MCP server and no MCP client, confirmed across the documentation corpus, both sitemaps and a DNS check, so agent-to-agent tooling is not available today.
• –Autonomous resolution is quoted at 60-80% for email, 70-80% when connected to systems of record and up to 90% on the G2 profile, so the figure depends on channel and setup.
• –AI replies pause when a plan's credit allowance is used up until credits are topped up, and the human agent inbox is a separately priced add-on from $19 per seat per month.

Pros

• ✓Co-founded by Bret Taylor, a former Salesforce co-CEO and OpenAI board chair, and Clay Bavor, an 18-year Google veteran who led Google Labs and Lens. Sierra has raised $1B+, most recently at a $15.8B valuation, and reported $200M in ARR in August 2026.
• ✓Outcome-based pricing charges per resolved interaction rather than per seat or conversation, so what a buyer pays tracks resolutions delivered rather than seats purchased.
• ✓Compliance covers FedRAMP High, SOC 2 Type II, ISO 27001, ISO 42001, AIUC-1, HIPAA, GDPR and CCPA, with named audit reports for SOC 2 and HIPAA available under NDA through the trust center.

Limitations

• –Sierra publishes no pricing page, no rate card, no minimum commitment and no per-outcome rate. Every commercial term including the definition of a resolved outcome is negotiated directly.
• –Deployment is sales-led with no self-serve signup. Published customer go-live timelines run from two to ten weeks, and integrations with proprietary systems need custom work through Sierra's integration framework or Agent SDK.
• –Sierra counts 40+ pre-built integrations but does not list them publicly, so buyers confirm coverage in a sales conversation. The MCP route is scoped to ChatGPT Apps, so teams standardizing on another MCP client have no documented endpoint.