inei

inei

EXIF and XMP metadata parser for JPEG, PNG, and HEIC/HEIF/AVIF. Written in TypeScript. Zero dependencies. Runs in browsers and Node.js.

Built as a modern replacement for exifr, which has been unmaintained since 2022.

Install

pnpm add inei

npm install inei

Quick start

import { parseExif } from "inei";

const buffer = await file.arrayBuffer();
const result = parseExif(buffer);

if (result.ok) {
  const { image, tags, xmp } = result.data;
}

parseExif returns a discriminated union. On success, result.ok is true and result.data contains the parsed metadata. On failure, result.ok is false and result.error is an ExifError with a code and message.

type Result =
  | { ok: true; data: ParsedExif }
  | { ok: false; error: ExifError };

Format support

Format	EXIF	Image size	XMP	Thumbnail
JPEG	Yes	Yes (SOF)	Yes (APP1)	Yes
PNG	Yes (eXIf chunk)	Yes (IHDR)	Yes (iTXt)	Yes
HEIC/HEIF/AVIF	Yes (ISOBMFF)	Yes (ispe)	Yes (mime item)	Yes

Format is auto-detected from magic bytes. You do not need to specify it.

API

parseExif(input, options?)

Synchronous. Accepts ArrayBuffer, Uint8Array, or Buffer.

import { parseExif } from "inei";

const result = parseExif(buffer);

parseExifFromBlob(input, options?)

Async. Accepts everything parseExif does, plus Blob and File. Use this in browsers when working with file inputs directly.

import { parseExifFromBlob } from "inei";

const input = document.querySelector("input[type=file]");
const file = input.files[0];
const result = await parseExifFromBlob(file);

gps(input)

Returns { latitude: number; longitude: number } or undefined.

import { gps } from "inei";

const coords = gps(buffer);
// { latitude: 37.7749, longitude: -122.4194 }

orientation(input)

Returns the EXIF orientation value (1-8) or undefined.

import { orientation } from "inei";

const o = orientation(buffer); // 1 = normal, 6 = rotated 90 CW, etc.

thumbnail(input)

Returns the embedded JPEG thumbnail as a Uint8Array, or undefined.

import { thumbnail } from "inei";

const bytes = thumbnail(buffer);

thumbnailUrl(input)

Browser only. Returns a blob: URL for the embedded thumbnail, or undefined.

import { thumbnailUrl } from "inei";

img.src = thumbnailUrl(buffer);

extractThumbnail(input, parsedExif)

Lower-level thumbnail extraction. Use this when you already have a ParsedExif result and want to avoid parsing twice.

import { parseExif, extractThumbnail } from "inei";

const result = parseExif(buffer);
if (result.ok && result.data.thumbnail) {
  const bytes = extractThumbnail(buffer, result.data);
}

Options

All options are optional. Defaults are shown.

parseExif(buffer, {
  readBinaryTags: false,    // Include UNDEFINED (binary blob) tags
  resolveTagNames: true,    // Map numeric tag IDs to human-readable names
  simplifyValues: true,     // Convert rationals to floats, dates to epoch seconds, GPS to decimal degrees
  imageSize: true,          // Extract width/height from container (SOF, IHDR, ispe)
  hidePointers: true,       // Omit internal IFD pointer tags (ExifOffset, GPSInfo, etc.)
  returnTags: true,         // Include the tag map in the result
  includeFormatted: false,  // Include pre-formatted strings for common tags
});

Result shape

type ParsedExif = {
  image?: { width: number; height: number };
  thumbnail?: ThumbnailInfo;
  tags: Partial<ExifTagMap>;       // Simplified values (numbers, strings, decimal degrees)
  tagsRaw: Record<string, unknown>; // Same keys, before simplification
  formattedTags?: Record<string, string>; // Only present when includeFormatted: true
  xmp?: XmpData;                   // Only present when XMP metadata exists
};

Tags

With simplifyValues: true (the default), values are post-processed:

• Rationals ([num, den]) become floats (num / den)
• Dates ("2023:10:22 18:46:07") become epoch seconds (1697999167)
• GPS DMS arrays become decimal degrees (37.7749)
• Timezone offsets are applied to date values

The tags object is typed as Partial<ExifTagMap>. Known tags have typed keys. Unknown tags appear as tag_0x{hex}.

EXIF tags extracted

Camera: Make, Model, Software, SerialNumber

Lens: LensMake, LensModel, LensInfo, LensSpecification, LensSerialNumber

Exposure: ExposureTime, FNumber, ExposureProgram, ISO, ExposureCompensation, ShutterSpeedValue, ApertureValue, MaxApertureValue, MeteringMode, Flash, ExposureMode

Focus: FocalLength, FocalLengthIn35mmFormat, FocalPlaneXResolution, FocalPlaneYResolution, FocalPlaneResolutionUnit

Image: ImageWidth, ImageHeight, Orientation, XResolution, YResolution, ResolutionUnit, ColorSpace, WhiteBalance, CustomRendered, SceneCaptureType

Date: DateTimeOriginal, CreateDate, ModifyDate, OffsetTime, OffsetTimeOriginal, OffsetTimeDigitized, SubSecTimeOriginal, SubSecTimeDigitized

GPS: GPSLatitude, GPSLongitude, GPSAltitude, GPSLatitudeRef, GPSLongitudeRef, GPSAltitudeRef, GPSTimeStamp, GPSDateStamp, GPSVersionID

XMP fields extracted

When present, result.data.xmp contains:

type XmpData = {
  title?: string;       // dc:title
  description?: string; // dc:description
  creator?: string;     // dc:creator
  subject?: string[];   // dc:subject (keywords/tags)
  rating?: number;      // xmp:Rating
  label?: string;       // xmp:Label
  createDate?: string;  // xmp:CreateDate
};

XMP is extracted from JPEG (APP1) and PNG (iTXt) automatically.

Formatted output

Pass includeFormatted: true to get human-readable strings for common tags:

const result = parseExif(buffer, { includeFormatted: true });
result.data.formattedTags;
// {
//   Shutter: "1/800",
//   Aperture: "f/10",
//   ISO: "ISO 400",
//   FocalLength: "50mm",
//   FocalLengthIn35mmFormat: "75mm",
//   ExposureCompensation: "0 EV",
//   ExposureProgram: "Normal program",
//   MeteringMode: "Multi-segment",
//   Flash: "Off, did not fire",
//   Orientation: "Normal",
//   GPS: "37.7749° N, 122.4194° W",
//   DateTimeOriginal: "Oct 22, 2023, 6:46 PM",
//   Make: "Canon",
//   Model: "EOS R6",
//   LensMake: "Canon",
//   LensModel: "RF50mm F1.2 L USM",
// }

Individual formatters

Available from inei/format:

import {
  formatShutter,
  formatAperture,
  formatFocalLength,
  formatDate,
  formatOrientation,
  formatExposureCompensation,
  formatExposureProgram,
  formatMeteringMode,
  formatFlash,
  formatGPSCoordinate,
} from "inei/format";

formatShutter(0.00125);            // "1/800"
formatAperture(2.8);               // "f/2.8"
formatFocalLength(50);             // "50mm"
formatDate(1697999167);            // "Oct 22, 2023, 6:46 PM"
formatOrientation(6);              // "Rotated 90° CW"
formatExposureCompensation(-0.7);  // "-0.7 EV"
formatExposureProgram(3);          // "Aperture priority"
formatMeteringMode(5);             // "Multi-segment"
formatFlash(0x10);                 // "Off, did not fire"
formatGPSCoordinate(37.77, -122.42); // "37.77° N, 122.42° W"

Batch formatter

Available from inei/format-tags:

import { computeFormattedTags } from "inei/format-tags";

const formatted = computeFormattedTags(result.data.tags);

Standalone XMP parser

Available from inei/xmp:

import { parseXmp } from "inei/xmp";

const data = parseXmp(xmlString);

Export paths

Path	Contents
inei	parseExif, parseExifFromBlob, gps, orientation, thumbnail, thumbnailUrl, extractThumbnail, ExifError, types
inei/format	Individual formatting functions
inei/format-tags	computeFormattedTags
inei/xmp	parseXmp, extractXmpFromApp1, extractXmpFromPngITxt

Error handling

parseExif never throws. It returns { ok: false, error } on failure.

const result = parseExif(buffer);
if (!result.ok) {
  console.error(result.error.code, result.error.message);
}

Error codes: NOT_JPEG, NO_EXIF, INVALID_TIFF, TRUNCATED, UNKNOWN.

The convenience functions (gps, orientation, thumbnail, thumbnailUrl) return undefined on failure.

Constraints

• ESM only. No CommonJS support.
• Reads the entire buffer into memory. No chunked or streaming reads.
• IPTC and ICC profile parsing are not supported.
• MakerNote data (vendor-specific extensions) is not decoded.

License

ISC