LLM Orchestration

ReLLM

Regular Expressions for Language Model Completions

Status
UnmaintainedNo commits in 1111 days.
Last checked
Checked · Oct 12, 2026
License
Open source
Pricing
Free tier · from $0
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What it is

ReLLM is a library that allows developers to use regular expressions with language model completions, enhancing the precision and control over generated text.

ReLLM stands out by offering a unique way to integrate regular expressions into language model completions, providing unparalleled control over the structure of generated text.

When it fits — and when it doesn’t

A good fit for

  • Developers needing precise control over the structure of generated text

  • Projects requiring adherence to specific formatting rules in content generation

  • Applications where regular expressions can enhance the utility of language model outputs

Look elsewhere if

  • Real-time applications with high latency requirements, as processing may be slower due to regex matching

  • Scenarios where minimal dependencies are required and only basic text generation is needed

Known weaknesses

Each one links to the public issue, changelog or docs page it came from, where we have one.

  1. 01

    Performance issues with complex regular expressions

    Benchmarking shows significant slowdowns when using nested or large regex patterns

What it does well

  • Integration of regular expressions with language model completions

  • Enhanced control over generated text through pattern matching

  • Flexibility in customizing output formats and structures

Pricing

Free tier
YesOpen source — free to use
Paid from
$0
Model
Flat rate
Enterprise plan
No

Pricing not independently confirmed — check the vendor’s page.

Performance benchmarks

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Setup steps, common gotchas and what to check after 30 days.

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