# Powerline

> Powerline builds tools that let AI agents — and the people working with them — act on the real world. The live product is **Inbox Preview**: paste an HTML email (or drop a `.eml`) and get pixel-accurate screenshots of how it renders in real, logged-in Gmail, Outlook.com and Yahoo Mail web sessions. Free, no sign-up. Same engine is available as a REST API, an MCP server and an agent skill.

Inbox Preview renders in the actual email client — a real logged-in mailbox, not an engine approximation — so what you see is what the recipient sees. Light and dark mode for Outlook and Yahoo (Gmail's message pane renders light regardless of theme). Screenshots are captured at a 1280px viewport. Job records and screenshots expire about 24 hours after the render, so copy or download anything you need to keep.

## Try it in a browser

- [Inbox Preview](https://powerline.ai/inbox-preview/): paste HTML or drop a `.eml`, renders in Gmail, Outlook and Yahoo at once. Free, no sign-up.
- [Preview HTML emails in Gmail (Web)](https://powerline.ai/inbox-preview/gmail): Gmail-only render, with notes on what Gmail strips from your CSS.
- [Preview HTML emails in Outlook (Web)](https://powerline.ai/inbox-preview/outlook): Outlook.com-only render, light and dark mode.
- [Preview HTML emails in Yahoo Mail (Web)](https://powerline.ai/inbox-preview/yahoo): Yahoo Mail-only render, light and dark mode.

## Use it from an agent or a pipeline

- [OpenAPI spec](https://api.powerline.ai/v1/openapi.yaml): the REST API. `POST https://api.powerline.ai/v1/jobs` with `html` or base64 `eml` plus a `renders[]` list, then poll `GET /v1/jobs/{job_id}` and fetch `GET /v1/jobs/{job_id}/screenshots/{filename}`. No API key or account is needed; the unguessable job id is the only credential for reading results.
- [MCP server](https://api.powerline.ai/v1/mcp): hosted Model Context Protocol endpoint (Streamable HTTP) with tools `list_clients`, `submit_preview`, `get_job`, `get_screenshot`. Point Claude Code, Claude Desktop, Cursor or any MCP client at the URL; nothing to install. Listed in the MCP Registry as `ai.powerline/inbox-preview`.
- [Agent skill (Markdown)](https://api.powerline.ai/v1/skills.md): LLM-readable instructions for using the service.
- [VS Code extension](https://github.com/powerline-ai/vscode-inbox-preview): open-source (MIT) client that renders the email you are editing.

## Free email tools

Deliverability checks that run in the browser, free and without sign-up. Each is also a JSON endpoint under `https://powerline.ai/api/tools/` and a tool on the MCP server below.

- [Email domain health check](https://powerline.ai/tools/domain-check): SPF, DKIM, DMARC, MX, MTA-STS, TLS-RPT, BIMI and blacklists in one run, scored out of 100 with a prioritized fix list.
- [SPF checker](https://powerline.ai/tools/spf-checker): validates the record, follows includes and counts DNS lookups against the limit of 10.
- [DKIM checker](https://powerline.ai/tools/dkim-checker): finds the key for a selector (or auto-detects common selectors) and checks its size and flags.
- [DMARC checker](https://powerline.ai/tools/dmarc-checker): policy, alignment, reporting addresses and external report authorization.
- [BIMI checker](https://powerline.ai/tools/bimi-checker): record, SVG Tiny PS logo, mark certificate and the DMARC prerequisite.
- [MTA-STS checker](https://powerline.ai/tools/mta-sts-checker) and [TLS-RPT checker](https://powerline.ai/tools/tls-rpt-checker): policy file, mode, max_age and MX coverage; TLS report destinations.
- [IP blacklist checker](https://powerline.ai/tools/ip-blacklist-checker) and [domain blacklist checker](https://powerline.ai/tools/domain-blacklist-checker): DNSBL and URI blacklist lookups, each list verified with its test entries so refused lookups are never reported as clean.
- [Email header analyzer](https://powerline.ai/tools/email-header-analyzer): delivery path with per-hop delays, SPF/DKIM/DMARC verdicts, DMARC alignment, one-click unsubscribe.
- [EML viewer](https://powerline.ai/tools/eml-viewer): opens .eml and .emlx files in the browser with inline images, headers, authentication and attachments.
- [DMARC report analyzer](https://powerline.ai/tools/dmarc-report-analyzer): reads aggregate report XML, .gz and .zip files; pass rate and failing sources.
- [Spam word checker](https://powerline.ai/tools/spam-word-checker): trigger phrases, ALL-CAPS, punctuation, emoji and URL shorteners, with a rule-based rewrite.
- [Email tools MCP server](https://powerline.ai/mcp): stateless Streamable HTTP endpoint with tools `check_domain`, `check_record`, `check_blacklists`, `analyze_headers`, `check_spam_words`. Endpoint list: [https://powerline.ai/api/tools](https://powerline.ai/api/tools).

## Company

- [Home](https://powerline.ai/): what Powerline is building.
- [Terms](https://powerline.ai/terms): terms of service for the free tool and the API.
- Contact: hello@powerline.ai