Product definition

What is Hex Fiend?

Hex Fiend is an open-source hex editor for macOS under the BSD-2-Clause licence. Its stated distinction is how it handles size: it does not read files into memory, so it opens a file as large as you can create — the project reports testing on one of 118 GB — and scrolling, copying and searching stay instant. Unlike editors that only allow in-place edits, it supports insertions and deletions, and writing back touches only the byte ranges that actually changed. It also ships a data inspector with endianness control, scriptable binary templates, and a two-file diff. It runs on macOS 10.11 and later.

Verified product facts

Type
hex editorEditorially reviewed
Platform
macOS
Pricing
Open sourceDeveloper-stated
Open source
Yes
Developer
Peter AmmonDeveloper-stated
Relationship to Nuanyue
Third-party product — not published by NuanyueEditorially reviewed
Licence
BSD-2-Clause
Current version
2.18.1Developer-stated
Official website
ridiculousfish.com/hexfiend/

Last updated . Facts marked developer-stated come from the developer and are not independently confirmed; editorially reviewed marks a Nuanyue judgement.

Key features

What Hex Fiend does at a glance.

  • Insert, delete, rearrange

    Hex Fiend does not limit you to in-place changes like some hex editors

  • Work with huge files. Hex Fiend can handle as big a file as you’re able to create. It’s been tested on files as large as 118 GB

  • Small footprint. Hex Fiend does not keep your files in memory. You won’t dread launching or working with Hex Fiend even on low-RAM machines

  • Fast. Open a huge file, scroll around, copy and paste, all instantly. Find what you’re looking for with fast searching

  • Smart saving

    Hex Fiend knows not to waste time overwriting the parts of your files that haven’t changed, and never needs temporary disk space

  • Data inspector

    Interpret data as integer or floating point, signed or unsigned, big or little endian

Common tasks

What you can use Hex Fiend for

  • Inspecting or patching the raw bytes of a binary file
  • Comparing two versions of a file byte by byte
  • Reading selected bytes as integers or floats with control over endianness
Audience

Who is Hex Fiend for?

  • Developers who need to look at or patch raw bytes in a file
  • Anyone debugging a binary format who wants a data inspector and binary templates
  • App developers who want to embed a hex view in their own application
Not a fit

Who is Hex Fiend not for?

  • Anyone who wants to read or edit prose — a text editor is the right tool for that
  • Users who want a guided, point-and-click interface rather than byte offsets

Strengths and trade-offs

What Hex Fiend does well, and what to weigh before choosing it. Points marked developer-stated come from the developer’s own material and have not been independently confirmed.

Strengths

  • Does not keep files in memory, so it opens a file as large as you can create; the project reports testing on a 118 GB file.
  • Supports insertions and deletions rather than only in-place changes, which it notes some hex editors limit you to.
  • Writing back overwrites only the byte ranges that changed, and the project states it never needs temporary disk space.
  • The project states its hex and data views can be embedded in another app through the Hex Fiend framework under a permissive licence.

Trade-offs

  • It is a byte-level tool: reading a file's structure means writing a binary template or interpreting raw offsets, and the data inspector only helps if you know how to read endianness.Editorially reviewed
  • Because it writes only the changed ranges back, there is no backup copy — the file you open is the file you edit.Editorially reviewed
  • The release tracked here is 2.18.1, dated 2025-03-16, so the feature set has not moved since.

What it does

Hex Fiend opens a file as raw bytes and lets you change them. Its stated distinction is how it handles size: it does not read the file into memory, so it will open a file as large as you can create — the project reports testing on one of 118 GB — and scrolling, copying and searching stay instant. Insertions and deletions are supported rather than only overwriting bytes in place, and writing back touches only the ranges you actually changed, with no temporary copy of the file.

Alongside the editor it ships a data inspector that reads the selected bytes as integers or floating-point values in either endianness, and binary templates — scripts that describe a file’s structure so it can be shown as fields rather than as bytes. Two files can be compared with File > Compare, which accounts for insertions and deletions rather than flagging every byte after an insertion as different.

The editor is BSD-2-Clause licensed, and the project states its hex and data views can be embedded in another application through the Hex Fiend framework. It runs on macOS 10.11 and later.

Questions about Hex Fiend

How large a file can Hex Fiend open?

The project reports testing on files as large as 118 GB and states that it does not keep files in memory.

Can Hex Fiend insert or delete bytes?

Yes. It supports insertions, deletions and rearranging rather than only overwriting bytes in place.

Is Hex Fiend free and open source?

Yes. It is published under the BSD-2-Clause licence.

Can I embed Hex Fiend in my own application?

The project states that its hex and data views can be incorporated into another app using the Hex Fiend framework, under a permissive licence.

Alternatives to Hex Fiend

Apps that could replace this one — the same job, a different trade-off.

  • ImHex

    Hex Editor for reverse engineers and programmers.

    Both are hex editors for developers. ImHex describes itself as being for reverse engineers and programmers; Hex Fiend's stated distinction is handling files too large to hold in memory.

    • Developer Tools
    • Free
    DetailsWebsite

Similar apps

Related in purpose, but not a straight swap.

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Sources

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