21st

21st

21st.dev
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About

21st is a developer platform that provides the fastest way to add AI agents directly into applications. The platform offers an SDK that allows developers to define, deploy, and run AI agents with minimal infrastructure setup. Developers can integrate agents using popular frameworks such as Next.js, React, TypeScript, Python, and Node.js. 21st includes built-in features like chat interfaces, session history, tool execution, memory, and real-time streaming responses. The platform also manages backend components such as sandboxed execution environments, authentication, rate limits, and observability. With support for Claude Code and Codex runtimes, developers can build agents that interact with tools, files, and APIs securely. By handling infrastructure and deployment automatically, 21st enables teams to launch production-ready AI agents quickly.

About

Paygent is the monetization and cost-tracking infrastructure platform built for AI-native businesses. Unlike legacy billing tools that only track revenue, Paygent gives AI companies real-time visibility into margins, infrastructure costs, and profitability per customer and per agent workflow. AI companies today operate across fragmented LLM providers, APIs, and cloud infrastructure, making it difficult to understand true unit economics. Teams often scale usage without realizing margins are shrinking. Paygent solves this by unifying real-time AI infrastructure cost attribution and automated billing into one platform. It tracks every LLM call, API request, and compute event tied to agent workflows, enabling customer-level gross profit visibility, automated billing, predictive pricing simulation, and cost alerts to prevent runaway agent loops. Built for AI startups, voice AI platforms, and autonomous agent teams, Paygent offers native SDKs for Node.js, Python, and Go.

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Audience

Software developers, startups, and product teams that want a fast and scalable way to build and deploy AI agents inside their applications

Audience

AI startups, voice AI companies, autonomous agent builders, LLM application developers, CTOs and AI engineers building agent-based products

Support

Phone Support
24/7 Live Support
Online

Support

Phone Support
24/7 Live Support
Online

API

Offers API

API

Offers API

Screenshots and Videos

Screenshots and Videos

Pricing

Free
Free Version
Free Trial

Pricing

$0/month
Free ($0/month) - 100K events, 1 year data retention, email support
Starter ($399/month) - 10M events, 7 year retention, 24/7 priority support
Growth ($799/month) - 25M events, 7 year retention, 24/7 priority support
Enterprise (Custom) - unlimited events, custom integrations, dedicated support
Free Version
Free Trial

Reviews/Ratings

Overall 0.0 / 5
ease 0.0 / 5
features 0.0 / 5
design 0.0 / 5
support 0.0 / 5

This software hasn't been reviewed yet. Be the first to provide a review:

Review this Software

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5
design 5.0 / 5
support 5.0 / 5

Pros & Cons from Real Users

Pros

  • - Handles genuinely complex billing logic - per-agent pricing, minimum monthly commitments, multi-line invoices with tax compliance (GST, TDS, HSN codes) - API-first design means our platform and Paygent stay in sync without any manual steps. Agents go live on our end, billing kicks in on theirs - Exposed a pricing API so our team could build configuration Uls directly into our admin portal - huge time saver - Order management, credit notes, and dispute workflows are all built in - The team understood our finance workflow: consumption data → quotation → PO → invoice, and built toward automating that entire chain - USD support available for international expansion
  • * Granular "Node-Level" Observability: Unlike Stripe, which sees a single monthly API bill, Paygent tracks costs at the graph node level. This allows you to pinpoint exactly which tool_call or llm_node is burning your budget. * Real-Time Margin Protection: It calculates the delta between what you charge a user and what the inference actually costs in milliseconds. If a recursive loop in your LangGraph starts eating your margin, Paygent can trigger an automated "circuit breaker" to pause the agent. * Vendor Agnostic Comparison: It normalizes billing data across OpenAI, Anthropic, and local models. You can see in real-time if switching a specific node from GPT-4o to Claude 3.5 Sonnet actually improves your unit economics. * Plug-and-Play for Agentic Frameworks: Paygent offers native SDKs for LangChain and LangGraph, meaning you don't have to write custom middleware to "tag" your metadata for billing; the infrastructure does it for you.
  • The founders are very responsive in solving real-time issues, and the feedback is seriously taken.

Cons

  • - Initial agent data sync needed some debugging cycles - timezone mismatches and STT data gaps took a few iterations to resolve - Integration setup required close collaboration; not a plug-and-play out- of-the-box tool (though this is understandable given the complexity)
  • The granular instrumentation required for a 50-node graph introduces a higher level of architectural complexity and a critical dependency on real-time financial telemetry that demands disciplined engineering oversight.
  • I hope we can move from their growth pro plan to enterprise at a slightly discounted rate, haha

Training

Documentation
Webinars
Live Online
In Person

Training

Documentation
Webinars
Live Online
In Person

Company Information

21st.dev
21st.dev/

Company Information

Paygent
Founded: 2026
India
www.withpaygent.com

Alternatives

Alternatives

Categories

Categories

Integrations

LiveKit
React
Tailwind CSS
Vapi AI
shadcn/ui

Integrations

LiveKit
React
Tailwind CSS
Vapi AI
shadcn/ui
Claim 21st and update features and information
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