fastdocparse

Extract structured data from semi-structured documents — invoices, bills, tax forms, resumes, bank statements, shipment manifests — using any OpenAI-compatible LLM (OpenAI, Ollama, vLLM, Groq, etc.), with per-field grounding and confidence, not just raw extraction.

Why this, not just another parser

Most extractors give you a value and no way to know if it's real. This one tells you:

• grounded — the value was found verbatim (or near-verbatim) in the source document text.
• ungrounded — the value doesn't appear in the source — likely a hallucination. Flag for human review.
• missing_required — a field you marked required came back empty.
• invalid_format — the value doesn't match a pattern/enum constraint you declared (e.g. a shipment status outside the allowed list).
• failed_check — a custom cross-field rule failed (e.g. line items don't sum to the stated total).

No extra LLM call for any of this — it's deterministic, string/rule-based validation against text you already extracted.

Where it fits: semi-structured documents with recurring fields (invoices, bills, tax forms, resumes, statements), and prose documents where proving a value came from the source matters (contracts, legal clauses, insurance claims). It is not a vision-LLM pipeline — it works from extracted text (digital PDF text layer, or local OCR for scans/images), which is what keeps it fast, cheap, and usable with small local models. Messy handwritten forms or complex multi-column layouts are a known weaker spot (see document-extractor-spec.md).

Two ways to use it

Defining what to extract also has two paths — hand-write a JSON/YAML schema file, or describe it in plain English and let the LLM draft the schema for you.

Install

pip install fastdocparse

For local development instead:

git clone https://github.com/pranjalparmar/fastdocparse
cd fastdocparse
python -m venv venv
source venv/bin/activate        # Windows: venv\Scripts\activate
pip install -e ".[dev]"

You also need access to an LLM. Either:

• An OpenAI API key (export OPENAI_API_KEY=... or pass --api-key), or
• A local model via Ollama — no API key, no cloud, documents never leave your machine.

Quickstart — CLI (no coding)

# 1. Extract using one of the bundled example schemas
fastdocparse extract sample_invoice.png src/fastdocparse/schemas/invoice.json \
  --model gpt-4o-mini --api-key sk-...

# Or with a local model via Ollama (no API key needed):
fastdocparse extract sample_invoice.png src/fastdocparse/schemas/invoice.json \
  --model llama3.2 --base-url http://localhost:11434/v1 --api-key ollama

Output is JSON, printed to stdout (or saved with --output result.json):

{
  "_meta": { "truncated": false, "truncation_reason": null },
  "invoice_number": { "value": "INV-9011", "confidence": "high", "flags": ["grounded"] },
  "total_price": { "value": 100.0, "confidence": "high", "flags": ["grounded"] }
}

Don't want to write JSON at all? Describe the fields in plain English instead:

fastdocparse schema-from-text \
  "I want the invoice number, total price, and vendor name. Invoice number and total are required." \
  --output my_invoice_schema.json

# review my_invoice_schema.json, then:
fastdocparse extract my_invoice.pdf my_invoice_schema.json

Quickstart — Python API

from fastdocparse import Schema, Field, LLMClient, DocumentParser

schema = Schema(
    name="Invoice",
    fields=[
        Field(name="invoice_number", description="The invoice number", required=True),
        Field(name="total_price", description="Total amount due", type="number", required=True),
    ],
)

client = LLMClient(model="gpt-4o-mini", api_key="sk-...")
# or: LLMClient(base_url="http://localhost:11434/v1", api_key="ollama", model="llama3.2")

parser = DocumentParser(client=client)

with open("invoice.pdf", "rb") as f:
    result = parser.extract(f.read(), schema)

print(result["invoice_number"])  # {'value': 'INV-9011', 'confidence': 'high', 'flags': ['grounded']}

Full documentation

• Getting Started — step-by-step install, CLI, and API walkthroughs
• Schema Guide — every field option (type, required, pattern, enum, sub_fields, few-shot examples), for JSON, YAML, and plain-English authoring
• Output & Validation — the full result shape, what each confidence flag means, and how to write custom cross-check rules
• Architecture — diagrams of the pipeline, the module dependency graph, and where to plug in a contribution
• Project spec — architecture, phased roadmap, honest competitive positioning

Want to contribute? Start with docs/architecture.md for the map, then CONTRIBUTING.md for the process.

Status

Core extraction, grounding, chunking, both CLI/API paths, and real packaging are implemented and tested (74 tests, pytest -v). Published on PyPI as fastdocparse — pip install fastdocparse installs a working fastdocparse command and a proper fastdocparse.* import namespace, verified end to end with a clean-virtualenv install straight from the real public index. Not yet done: a hosted API — see document-extractor-spec.md for the roadmap.