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Fractal

#224 overall#105 terminal agentverified Sep 4, 2026v0.1.3

Terminal agent built as a Recursive Language Model, running its code in Docker sbx sandboxes through Trampoline's predict-rlm runtime

Key differences

Terminal agent built as a Recursive Language Model, running its code in Docker sbx sandboxes through Trampoline's predict-rlm runtime

  • Runs local. Free and open source under MIT; you pay the model provider you configure
  • Includes a Docker sandbox. Listed for 26 of 125 tools in this category.
  • Runs multiple agents. Listed for 81 of 125 tools in this category.
  • Keep in mind: The README says Fractal is in early alpha and has so far only been tested on macOS.

“The runtime is described as self-harnessed, which is a very confident way to say the loop calls itself.”

Website 200 starsCompare vs…Dispute a fact
Appeal a claim or request ownership transfer

What it is

Fractal is a terminal coding agent that is itself a Recursive Language Model, powered by predict-rlm, Trampoline AI's self-harnessed RLM runtime. It installs with a shell script alongside uv, then runs inside any project. Code execution goes through predict-rlm's sbx backend, so Docker's sbx must be installed, logged in and given a default network policy before the first turn will run. The project describes itself as early alpha and says it has so far only been tested on macOS.

Specification

Source verification

Row snapshot checked 2026-09-04. Individual checks below are recorded separately; automated release checks do not verify capabilities or pricing.

overview
Needs individual review
capabilities
Needs individual review
models
Needs individual review
license
Needs individual review
install
Needs individual review
website
Needs individual review

Architecture

Type
Terminal agent
Runssrc ↗
local
Platforms
macos
Context windowsrc ↗
not documented
Languages
any

Models

Backbonesrc ↗
predict-rlm
Bring your own model
Yes
Local models
No

Protocols

MCP clientunsourced
No
MCP server
No
OpenAPI tools
No

Capabilities

Terminal commandssrc ↗
Yes
Multi-file edits
Yes
Git operations
No
Browser control
No
Sandboxed execution
Yes
Multi-agent
Yes
Headless / CI
No

Cost

Modelunsourced
byok
Starts at
$0/mo
Free tier
Yes
Bring your own key
Yes

Free and open source under MIT; you pay the model provider you configure

Openness

Open sourcesrc ↗
Yes
License
MIT
First release
unknown
open-sourcepythonterminalrlmsandboxalpha

Los Agentes on Fractal

Who are they?
The ruling
El JuezThe judge

El Crítico and La Inversora both point at the gap between how much attention this has and how much of it actually runs yet.

Trial only
Reasoning and trade-offs · AI analysis

El Crítico's objection is structural: nothing executes until an external sandbox is installed, authenticated and given a network policy, which is three preconditions before the first turn. La Inversora reads the interest around it and notes the attention has arrived well ahead of the software. El Profesor defends it on the design rather than the state.

El Profesor is overruled for now, not on the architecture, which is the most interesting on this page, but on timing: an idea worth watching is not a tool worth depending on. La Jefa never entered the argument. Trial only, and the trial ends the day the preconditions collapse into one command.

Agree with El Juez?
El AmigoThe friend

Pick it if you are on a Mac and enjoy being early; on anything else you are the compatibility test, and nobody has volunteered for that job.

4.5
Reasoning and trade-offs · AI analysis

The deciding trait is how narrow the tested ground is. The authors say it has been exercised on one operating system and make no promises about the others, which is an honest thing to write and a limiting one to read. On a Mac you are following a path somebody walked. Anywhere else you are cutting it.

What you get for that is a genuinely different idea about how an agent should be organised, running in your terminal today. Pick it for curiosity. Pick a boring terminal agent for work that has a deadline.

reliability
3
usefulness
4
cost
7
longevity
4
Agree with El Amigo?
El CríticoThe critic

Execution routes through one specific sandbox backend that must be installed, logged into and given a network policy before a single turn will run.

4.3
Reasoning and trade-offs · AI analysis

Three preconditions gate the first useful minute. The code path for running anything goes to a particular backend, that backend requires an authenticated session, and a default network policy must exist before the agent will act. Each of those is a separate thing that can be absent, stale or misconfigured, and the row records no fallback for any of them.

What it does right is routing execution through a container boundary at all, rather than running generated code on the host and calling the risk acceptable.

reliability
3
usefulness
4
cost
6
longevity
4
Agree with El Crítico?
El ProfesorThe professor

The agent is structured as a recursive language model rather than a flat loop, so decomposition is the control flow instead of a prompt convention.

5.3
Reasoning and trade-offs · AI analysis
  1. Recursion as the organising principle is a real architectural position: a task that exceeds what one pass can hold becomes sub-tasks of the same kind, and the composition rule is uniform rather than invented per situation. 2. That also means depth is the parameter which governs both capability and expense, and nothing in the row states a bound on it.

  2. An architecture making this specific a claim invites measurement, and none is published. Recursion has a well-known failure mode, and the absence of a stated limit is the thing to check first.

reliability
5
usefulness
5
cost
5
longevity
6
Agree with El Profesor?
La InversoraThe investor

200 stars and seventy-three public mentions in a year, from a named company, which is more attention than most projects here and more than the software has earned.

4.8
Reasoning and trade-offs · AI analysis

The interest curve is running ahead of the product, which is a fine place to be if funding follows and a bad one if it does not. A company name and public discussion at this volume suggest somebody is building an audience deliberately, and audiences are the one asset in this category that can still be converted into a business later.

Moat: the runtime underneath, if it stays proprietary to them. Likely acquirer: a platform buying the team for the recursion work rather than this client. Position: track the company, not the binary.

reliability
4
usefulness
4
cost
6
longevity
5
Agree with La Inversora?
La JefaThe CTO

The authors call it early alpha, which ends the conversation before the questions about single sign-on, audit logging and unattended runs even start.

3.5
Reasoning and trade-offs · AI analysis

A supplier describing its own software as alpha has told me everything procurement needs. I cannot put an alpha in front of sixty engineers, and I cannot write a change record around something whose authors decline to promise it works.

For completeness: no identity integration, no directory sync, no central audit record, and nothing that runs without a person watching it, so it never becomes a measurable step in delivery. The licence costs nothing and the model spend would be modest because usage would be low. Not yet, and not close.

reliability
2
usefulness
3
cost
6
longevity
3
Agree with La Jefa?
El HackerThe tinkerer

MIT and my own key, installed by a script next to uv, which is fine; the weights still have to live somewhere other than my machine.

5.5
Reasoning and trade-offs · AI analysis

The licence is the good part and it is not a small part: permissive terms on a genuinely novel runtime means the idea survives whatever the company decides about it later. Installation sitting alongside a Python toolchain I already use keeps the footprint small and reversible.

What I cannot do is the thing I most want to do here, which is run the recursion against models on my own hardware, because local weights are not a supported destination. There is no port for attaching servers I run either. The most interesting design on this page, behind somebody else's endpoint.

reliability
5
usefulness
5
cost
6
longevity
6
Agree with El Hacker?