AI tool comparison
Azure Foundry Hosted Agents vs Libretto
Which one should you ship with? Here is the side-by-side panel verdict, pricing read, reviewer split, and community vote comparison.
Developer Tools
Azure Foundry Hosted Agents
Per-session isolated agent sandboxes on Azure — scale to zero, any framework
50%
Panel ship
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Community
Paid
Entry
Microsoft Azure's Foundry Agent Service now offers Hosted Agents in public preview — per-session isolated compute sandboxes purpose-built for running AI agents at scale. Each session gets its own container with a persistent filesystem, internet access (optional), and a Python environment pre-loaded with common agent dependencies. Sessions spin up in seconds and terminate — and stop billing — the moment the agent task completes. The design is framework-agnostic: it officially supports LangGraph, OpenAI Agents SDK, Claude Agent SDK, and Microsoft's own Agent Framework, with others planned. This removes one of the most awkward parts of deploying agents in production: figuring out where they actually run. The persistent filesystem per session means agents can read and write files across their task without external storage configuration. Pricing is $0.0994/vCPU-hour and $0.0118/GiB-hour — competitive with Lambda/Cloud Run for bursty workloads. The service is available in six Azure regions at launch. For enterprises already invested in Azure, this is a compelling "we just figured out the infra" moment. Independent developers can also use it without an enterprise agreement.
Developer Tools
Libretto
AI browser automation that doesn't break every other deploy
75%
Panel ship
—
Community
Paid
Entry
Libretto is an open-source TypeScript toolkit for building and maintaining browser automations that are actually reliable. Unlike most AI-driven browser tools that use probabilistic reasoning to select elements at runtime, Libretto works by having the AI generate deterministic selectors and action sequences upfront — then executing them with zero LLM involvement at runtime. The AI is your authoring tool, not your runtime dependency. The core insight: most AI browser automations fail in production because they call an LLM on every page interaction. Libretto flips this by using AI to write and update the automation scripts, but running them as ordinary code. When a site changes and your automation breaks, Libretto detects the failure and prompts you to let AI update the selector — then it's deterministic again. Built by the team at Saffron Health, the library hit HN's front page today and is generating discussion as a more pragmatic alternative to fully autonomous browser agents. For anyone who's tried Playwright with AI wrappers and found them unreliable in CI/CD, this is the architecture that's been missing.
Reviewer scorecard
“Framework-agnostic hosted sandboxes with scale-to-zero is exactly what I need for deploying agents without maintaining my own Kubernetes cluster. The per-session isolation eliminates a whole class of security concerns I was handling manually. The Claude Agent SDK support means I don't have to choose between Azure and my preferred model.”
“This is the right mental model for production browser automation. Using AI for authoring but not runtime means you get consistency in CI without random failures at 2am. I've been waiting for someone to build this properly.”
“Public preview means production instability risk and pricing could change significantly at GA. The cold start time for agent sessions needs to be benchmarked against real workloads before committing. And six regions is thin coverage for global deployments — wait for broader availability.”
“The 'AI updates your selectors' workflow sounds great until you're reviewing 50 AI-generated selector changes after a site redesign. You've just moved the flakiness from runtime to the maintenance loop. Also, 37 stars is very early — I'd wait for production case studies.”
“The battle for agent infrastructure is the next cloud wars — and Microsoft just answered Google Cloud's agent platform launch with their own. Framework-agnostic compute that works with any model provider is a smart commoditization play: own the infrastructure layer, let the model battle play out above it.”
“The deterministic-at-runtime pattern will become the standard architecture for AI-assisted automation. Libretto is arriving exactly as enterprises start demanding reliability SLAs from their AI tooling. Early movers will have a significant advantage.”
“This is squarely developer infrastructure — not directly relevant to creative workflows unless your studio runs its own agents. Worth watching for the ecosystem tools that get built on top of it.”
“As someone who automates repetitive web tasks constantly, this solves my biggest frustration — AI-written automations that fall apart the moment a site updates their CSS. The auto-repair loop is exactly what I need for long-running workflows.”
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