Open Harness vs Presto Voice

Side-by-side comparison of features, pricing, and ratings

Analysis reviewed Live tool data as of 2026-10-10
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At a glance

DimensionOpen HarnessPresto Voice
Target AudienceDevelopers building AI agentsQSR chains with drive-thrus
PricingFree (open-source SDK)Contact sales (enterprise)
Core CapabilityCode-first agent framework (TypeScript)Voice AI for drive-thru ordering
Key DifferentiatorComposable middleware, hierarchical subagentsUpselling engine with 88% offer acceptance
IntegrationsVercel AI SDK, OpenAI, Anthropic, Google, MCPElevenLabs, POS, headset systems
Latest NewsNo recent newsDairy Queen adopts Presto Voice AI (2026-04-16)

Choose Open Harness if you're a developer needing a flexible, code-driven SDK to build custom AI agents with fine-grained control over state and middleware. Choose Presto Voice if you're a QSR chain operator seeking a proven, drive-thru-specific voice AI solution that boosts revenue through automation and upselling—especially with recent adoption by large brands like Dairy Queen.

Open Harness
Open Harness

Open Harness is an MIT-licensed TypeScript SDK for building Claude Code-style agents with stateless primitives and composable middleware.

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Presto Voice
Presto Voice

Presto Voice is drive-thru voice AI that answers the speaker post, takes the order, and upsells every car.

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Pricing
Free
Contact Sales
Plans
$0/mo
—
Popularity
7 views
7.5k views
Skill Level
Advanced
Intermediate
API Available
Platforms
WebCLI
API
Categories
🕸️ Agent Frameworks & Orchestration📦 LLM App Frameworks & SDKs🔌 MCP Servers & Agent Tooling
🍽️ Restaurant & Hospitality☎️ Voice AI Agents & Phone Automation
Features
Stateless agents with message history as plain arrays
Composable middleware for turn tracking, retry, compaction, persistence
Hierarchical subagents with background execution and Promise-like combinators
Two-phase context compaction: prune old tool results, then LLM summarization
Async tool permission callbacks for gating execution (approve hook)
MCP integration over stdio, HTTP, or SSE transport
On-demand SKILL.md instruction loading
Automatic AGENTS.md and CLAUDE.md project context injection
Built-in filesystem tools via NodeFsProvider
Built-in bash tool via NodeShellProvider
Typed event streaming (text.delta, tool.done, done) to CLI or web UIs
React hooks for web UIs
Vue composables for web UIs
Any model provider via Vercel AI SDK (OpenAI, Anthropic, Google)
Runs on Node.js and edge runtimes
Automated drive-thru order taking via voice AI at the speaker post
Continuous upselling of add-ons and specials to raise average order value
Runs a spectrum of Voice AI approaches rather than a single model
Up to 95% non-intervention rate on drive-thru orders (vendor-published)
Up to 88% upsell offer rate (vendor-published)
Up to 6% monthly incremental revenue increase (vendor-published)
24/7 drive-thru ordering availability
Installation at scale without disrupting live drive-thru lanes
POS and headset provider integration handled by Presto (integration specialist)
Available through the Toast Partner Ecosystem (Sept. 21, 2026)
Managed deployment with ongoing vendor support
ROI reporting across non-intervention, upsell, and revenue lift
Nationwide rollout experience at Wienerschnitzel, Taco John's, and Dairy Queen
15+ years of restaurant drive-thru automation experience since 2008
Integrations
OpenAI
Anthropic
Google
Model Context Protocol
Vercel AI SDK
Toast

What real users say: Open Harness vs Presto Voice

Not marketing copy and not our opinion — a structured sweep of public discussion (reviews, forums, communities and video comments), showing what people praise and what they complain about for each tool.

Open Harness

30 mentions across 2 sources · 50% positive — mixed (averaged across 2 sources)

Hacker News, Lemmy

What users praise

  • • Composable middleware for stateless agent building.
  • • Full control over message history and tool execution.
  • • Model-agnostic — works with any provider via Vercel AI SDK.
  • • Hierarchical subagents with background execution support.

What frustrates them

  • • Very early-stage with limited real-world validation.
  • • Small community — support relies on GitHub issues.
  • • Anthropic's open-sourced agent reduces differentiation.
  • • Requires TypeScript proficiency; not beginner-friendly.

Researched Jul 3, 2026

Presto Voice

45 mentions across 3 sources · 32% positive — critical (weighted across 3 sources)

YouTube, App Store, Lemmy

What users praise

  • • Fifteen-plus years in restaurant automation gives Presto real QSR operational experience
  • • Handles POS and headset provider integration itself, avoiding a lane shutdown at install
  • • National rollouts at Wienerschnitzel, Taco John's, and Dairy Queen validate enterprise scale
  • • Spectrum-of-models approach targets store-by-store variation in menus, accents, and ambient noise

What frustrates them

  • • No independent operator reviews exist in the public data to validate the 95% claim
  • • Vendor-published metrics lack third-party audited baselines or methodology
  • • Only Toast is named as an integration — other POS stacks are unproven
  • • Pricing is undisclosed, making per-lane ROI modeling impossible up front

Researched Oct 7, 2026

Who should pick which

  • QSR chain operator
    Pick: Presto Voice

    Presto Voice directly automates drive-thru ordering, increases average order value via upselling (up to 88% acceptance), and integrates with existing POS/headset systems. Recent Dairy Queen adoption validates its enterprise readiness.

  • Developer building a coding agent
    Pick: Open Harness

    Open Harness provides a composable, TypeScript SDK with hierarchical subagents and context compaction—ideal for creating stateless agent pipelines for IDEs or CLI assistants.

  • Independent QSR restaurant owner
    Pick: Presto Voice

    Despite contact pricing, Presto Voice's upselling engine and 95% automation can quickly pay off for a single location if drive-thru volume is high.

  • AI researcher prototyping agent architectures
    Pick: Open Harness

    Open Harness's middleware system and full message control allow experimentation with custom agent behaviors without framework lock-in.

  • Franchise network scaling voice AI
    Pick: Presto Voice

    Presto Voice is built for multi-location deployment with minimal disruption, menu unification, and measurable ROI, making it suitable for franchise operations.

Frequently Asked Questions

Open Harness vs Presto Voice: which should you choose?

Choose Open Harness if you're a developer needing a flexible, code-driven SDK to build custom AI agents with fine-grained control over state and middleware. Choose Presto Voice if you're a QSR chain operator seeking a proven, drive-thru-specific voice AI solution that boosts revenue through automation and upselling—especially with recent adoption by large brands like Dairy Queen.

Can I use Open Harness for a non-TypeScript project?

Open Harness is TypeScript-first with full type safety. It can be used in JavaScript projects, but it is not available for Python or other languages.

Does Presto Voice require hardware installation?

Presto Voice integrates with existing POS and headset systems, so installation is primarily software-based. It can be deployed with minimal disruption across multiple locations.

Is Open Harness suitable for production use?

Yes, it's built on Vercel AI SDK and supports Node.js, edge, and browser runtimes. However, as an open-source tool, you are responsible for hosting and scaling.

What is the typical ROI for Presto Voice?

Presto Voice claims up to 6% monthly incremental revenue and up to 88% offer acceptance rates via upselling, with measurable lift in average order value.

Can Open Harness agents have memory?

Open Harness is stateless by design. For memory, you would need to implement persistence via middleware or an external store.

Does Presto Voice support phone ordering?

Yes, Presto Voice includes phone ordering automation alongside drive-thru capabilities.

Which AI models does Open Harness support?

Open Harness supports any model provider through the Vercel AI SDK, including OpenAI, Anthropic, Google, and others.

Has Presto Voice been adopted by major chains?

Yes, recent news (April 2026) confirms Dairy Queen has partnered with Presto. Past customers include Taco John's and The Galardi Group.

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Last reviewed: July 3, 2026