EML File Viewer

How to use

1. 1Click Open .eml file and pick a message saved from Outlook, Apple Mail, Thunderbird, Gmail, or any mailer. The file is read in your browser. Nothing is uploaded.
2. 2Use the Load sample button if you want to see the layout with a known multipart message before opening your own file.
3. 3Read the Summary tab for the standard fields (From, To, Cc, Subject, Date, Message-ID) and a quick card showing how many headers and attachments the message has.
4. 4Switch to the Text body or HTML body tab. The HTML body is rendered inside a sandboxed iframe so scripts and external requests are blocked. Inline cid: images are rewritten to local previews.
5. 5Open the Headers tab to inspect every header with its decoded value. Use the Copy raw headers button to grab the original header block.
6. 6Open the Attachments tab and click Download next to any attachment. The file is rebuilt from the bytes inside the .eml on your device.
7. 7Or paste a raw message into the textarea if you only have the source text rather than a file.

About this tool

EML File Viewer opens an .eml message in your browser and shows the headers, decoded text and HTML bodies, and any attachments. An .eml file is the raw RFC 5322 / MIME source of an email, the same format Outlook, Apple Mail, Thunderbird, Gmail, and most automated mailers use when they export or save a single message. People hit this file type often without an email client at hand: a forwarded incident report saved to disk, a bounce report dropped into a ticket, a customer complaint exported from a CRM, a phishing sample handed to a security team, or a message extracted from a backup archive. The viewer parses the file locally with a tolerant RFC 5322 and MIME parser. It splits the headers from the body, unfolds folded header continuation lines, walks the multipart MIME tree by following the boundary parameter on each Content-Type, and decodes each leaf part using its declared Content-Transfer-Encoding (7bit, 8bit, binary, quoted-printable, or base64). Text parts are then re-decoded with TextDecoder using their declared charset, defaulting to UTF-8, so subjects with non-Latin characters and quoted-printable bodies show as readable Unicode. RFC 2047 encoded words in header fields (=?utf-8?B?...?= and =?utf-8?Q?...?=) are decoded so From, To, Cc, Subject, and attachment filenames render correctly even when the original sender used a non-ASCII charset. The Summary tab shows the standard fields (From, To, Cc, Bcc, Reply-To, Subject, Date, Message-ID) plus a quick at-a-glance card with the header count, attachment count, and which body types are present. The Text body and HTML body tabs render the decoded content; the HTML body is shown inside a sandboxed iframe with sandbox="" (an empty allowlist) so scripts, forms, plugins, and same-origin access are all blocked, and inline images that the email references with cid: URLs are rewritten to local data URLs so the rendered email looks correct without making any network request. The Headers tab lists every header in original order with its decoded value and a copy button for the raw header block. The Attachments tab lists every attachment with its filename, MIME type, and size, and each attachment can be downloaded with a single click; the download is built from the bytes inside the .eml itself, not fetched from the network. The whole pipeline runs on your device. The file is opened with the browser FileReader API as an ArrayBuffer, no upload, no server, no third-party service. That matters because .eml files routinely carry private content (real names, customer data, internal hostnames, ticket IDs, security samples) that should not be pasted into a stranger's web service. Use this tool any time you receive an .eml attachment and need to read it without installing Outlook or Thunderbird, audit the headers of a suspicious message, recover attachments from a saved message, inspect a bounce report or NDR, or quickly preview a marketing email export without sending it.

Free to use. Works in your browser. No signup, no login.