Project Lion - Senior Prompt Engineer - Spain (Remote, Part-Time)

Welo Global; United States; Remote; USD 110,000 - 180,000; Full time

Job summary

Welo Global is seeking a Prompt Engineer to own the end-to-end migration workflow for translating templates into LLM-driven autoraters. You will leverage internal APG and APO tools to maximize model performance and ensure robust, structured outputs.

You will combine automated tooling with manual prompt engineering, handle edge cases, and document launch readiness. Native Spanish with fluent English is required, and a relevant advanced degree is expected.

Qualifications

• Native Spanish and fluent English required.
• Bachelor’s, Master’s, or Doctorate in Computer Science, Data Science, Computational Linguistics, HCI, Cognitive Science, or related analytical field.
• 4+ years’ experience as Prompt Engineer with LLM tuning for structured outputs.
• Proficient in data analysis and SQL or similar analytics tools.
• Ability to quickly learn proprietary tools with minimal supervision.
• Excellent verbal and written communication skills.

Responsibilities

• Utilize APG tools to create baseline prompts for complex template clusters.
• Run and supervise Automated Prompt Optimization (APO) tool, review outputs and flag deadlocks or plateaus.
• Manually draft, test, and refine prompts for complex template architectures and edge cases.
• Solve edge-case scenarios by designing and refining manual prompts.
• Monitor shadowbot runs to ensure disagreements are registered and tracked.
• Run prompts against gold data to measure autorater quality and metrics (F1, precision, recall).
• Draft Launch Certification Documentation for final release.

Skills

Spanish (native)

English (fluent)

Data analysis

SQL

Prompt engineering

LLM tuning

Communication

Education

Related analytical field degree

Tools

APG tools

Automated Prompt Optimization (APO)

Goose API

Job description

We are seeking a Prompt Engineer to be responsible for the end-to-end technical migration workflow for transitioning templates to LLMautoraters. The role is required to use client’s internal tools to leverage prompt engineering techniques to maximize model performance.

Responsibilities

• Utilize Automatic Prompt Generation (APG) tools to create baseline prompts for complex parent-child template clusters.
• Run and supervise Automated Prompt Optimization (APO) tool, review the outputs, and flag when the APO reaches deadlocks or plateaus.
• Manuallydraft, test, and refine prompts to navigate complex template architectures, overcome anti-patterns, and handle edge cases where tooling is lacking or broken.
• Solve edge-case scenarios by designing and refining manual prompts.
• Monitorshadowbotruns to ensure sufficient disagreements (between human and LLM ratings) are registered, generated, and tracked.
• Run prompt versions against established gold data to continuously measureautoraterquality against the human crowd baseline, calculating accuracy metrics such as F1 scores, precision, and recall.
• Draft technical launch readiness justifications (Launch Certification Documentation) for final.

Requirement

• Language Skills: Native fluency in Spanish and fluent in English.
• Location: Must be based in Spain.
• Education: Bachelor’s, Master’s, or Doctorate degree in Computer Science, Data Science, Computational Linguistics, Human-Computer Interaction (HCI), Cognitive Science, ora relatedanalytical field.
• Prompt Engineering & AI Expertise: At least 4 years' experience as Prompt Engineer. Proven experience tuning Large Language Models (LLMs)for strict, structured outputs, complex classification tasks, and familiarity with chain-of-thought and few-shot learning.
• Data Analysis: Strongproficiencyinidentifyingerror patterns, analyzing model performance, and using SQL or other data analytics tools.
• Technical Agility: Ability to quickly learn and master proprietary tools with minimal supervision.
• Communication: Excellent verbal and written communication skills.

Optional / Preferred Skills

• Familiarity with enterprise-grade LLM interfaces like the Goose API.
• Experience in AI model evaluation, data science, computational linguistics, or software engineering.
• Hands-on experience with Automated Prompt Optimization (APO) systems or tuning workflows.
• Linguistic expertise, including an understanding of semantics and logic.