pdfspine 0.0.1

Apache-2.0-licensed, pure-Rust reimplementation of PyMuPDF (fitz) with PyO3 bindings.

pdfspine

An Apache-2.0-licensed, pure-Rust reimplementation of PyMuPDF (fitz), with PyO3 Python bindings.

🦴 Part of the spine family — framework-free backend engines, each the spine of a domain: zero framework lock-in, Protocol-ized seams, offline-capable. pdfspine is the PDF spine (this repo); ragspine is the RAG spine (deterministic dual-channel retrieval + agent orchestration).

Status: alpha / pre-1.0, but the core is feature-complete. pdfspine can already parse/repair/decrypt PDFs, extract text & tables, search, edit / merge / split / save (incl. byte-exact incremental), encrypt, annotate, fill & flatten forms, redact (destructively), open image files as documents, render pages to images, and OCR (Tesseract + a pure-Rust PaddleOCR engine, stronger on CJK). 88.7% (682 / 769) of the PyMuPDF 1.24 public API is implemented and tested (climbing), with 1349+ Rust tests + 593+ Python tests green. Text extraction is at fitz parity (and beats fitz on Arabic / RTL), rendering is near-parity and ~1.74× faster, and the pure-Rust PaddleOCR engine beats fitz on CJK scans (see Accuracy). Not yet on PyPI — build from source for now.

---

Why pdfspine?

PyMuPDF is excellent, but it is AGPL-3.0 (or a commercial license from Artifex) — a non-starter for many closed-source products, SaaS backends, and permissively-licensed open-source projects.

pdfspine is a drop-in-shaped, permissively-licensed (Apache-2.0) alternative:

• Apache-2.0 throughout — permissive, with an explicit patent grant. The dependency graph is gated by cargo-deny to exclude GPL / AGPL / LGPL / MPL / SSPL from the shipped wheel. License cleanliness is CI-enforced, not a promise.
• Pure Rust, no C blob. Self-contained wheels, no system zlib/C linkage, no bundled prebuilt engine (the differentiator vs pdfium-based wrappers).
• import fitz compatible (opt-in). A compatibility shim lets much existing PyMuPDF code run unmodified — available as import pdfspine.fitz as fitz, or registered under the global fitz / pymupdf names with one call to pdfspine.install_fitz_shim(). A default install is collision-safe: it does not claim those global names, so it coexists with a real PyMuPDF in the same environment. A machine-readable COMPAT.toml documents every symbol's status.
• Memory-safe by construction. #![forbid(unsafe_code)] in every first-party crate except the single audited PyO3 FFI chokepoint.
• Clean-room. No code, tests, or fixtures derived from MuPDF / PyMuPDF / any AGPL source.

What works today

Area	Capabilities
Read	open (file/bytes), malformed-PDF repair, encrypted PDFs (RC4 / AES-128 / AES-256, R2–R6)
Text	get_text (text/words/blocks/dict/rawdict/json/html/xhtml/xml), search_for, TextPage, fonts/images inventory
Tables	find_tables with merged-cell detection → extract() / to_markdown() / to_html()
Edit & save	full + byte-exact incremental save, garbage collection, page insert/delete/copy/move/select, insert_pdf merge, metadata/XMP, TOC, links, encryption write
Annotate	all common annotation types with /AP appearance streams; AcroForm read / fill / flatten + Widget; destructive redaction (verified content removal)
Render	get_pixmap (vector + text + image + shadings via a tiny-skia rasterizer), Pixmap (buffer-protocol/numpy), DisplayList, get_svg_image
Images	open PNG/JPEG/TIFF/GIF/BMP/WEBP as documents, convert_to_pdf, image-XObject decode (DCT/CCITT/JBIG2/JPX), extract_image
Layers	Optional Content Groups read/write (get_ocgs / add_ocg / set_layer)
OCR	pluggable engine: Tesseract adapter and a pure-Rust PaddleOCR engine (PP-OCRv4, embedded models, stronger on CJK) → searchable-sandwich PDF
CLI	pdfspine info / text / render / merge / split / pages / images / toc

Planned next: reading-order accuracy improvements, Type1/Type3 glyph rendering, broader CJK coverage. See PRD.md / docs/ROADMAP.md. Out of scope: digital-signature creation.

Quick start

import pdfspine

doc = pdfspine.open("input.pdf")
print(len(doc), "pages", doc.metadata)

page = doc[0]
print(page.get_text())                       # plain text
print(page.search_for("invoice"))            # list[Rect]
page.get_pixmap(dpi=150).save("page1.png")   # render to image

tables = page.find_tables()
for t in tables.tables:
    print(t.to_markdown())                    # or t.to_html() for merged cells

doc.save("output.pdf", garbage=4, deflate=True)

Existing PyMuPDF code often runs unchanged via the opt-in compat shim:

import pdfspine.fitz as fitz                  # the shim, no global-name collision
doc = fitz.open("input.pdf")
text = doc[0].get_text("dict")

# Or make the literal `import fitz` resolve to the shim (one-time opt-in):
import pdfspine
pdfspine.install_fitz_shim()
import fitz                                    # now -> pdfspine's fitz shim

A default install does not claim the global fitz / pymupdf names, so it is safe alongside a real PyMuPDF; install_fitz_shim() uses setdefault and never clobbers a PyMuPDF you imported first.

Command line:

pdfspine info report.pdf
pdfspine text report.pdf --pages 1-3 --format json -o out.json
pdfspine render report.pdf --dpi 200 -o images/
pdfspine merge a.pdf b.pdf -o merged.pdf

Accuracy

Validated against an objective ground-truth harness and with PyMuPDF (fitz) as the differential oracle (clean-room: the AGPL oracle is run locally only and never committed). See docs/BENCHMARKS.md and the conformance/gt/ reports for the dated, reproducible evidence.

• Text extraction is at fitz parity on born-digital corpora, and beats fitz on Arabic / RTL (correct bidi reordering).
• Rendering is near-parity with fitz (page-image SSIM ~0.945) and ~1.74× faster after a font-cache fix.
• OCR beats fitz on CJK scans: the pure-Rust PaddleOCR engine (PP-OCRv4, with models embedded in the wheel) outperforms fitz's OCR path on Chinese/Japanese/ Korean documents.
• Real-corpus robustness: open rate 100%, 0 panics/hangs, re-saved files 100% qpdf --check-clean across the public-domain US-government corpus.

Remaining accuracy work (multi-column reading order, Type1/Type3 glyph rendering, broader CJK) is tracked in docs/PRD-NEXT.md.

Build & install

Requirements: Rust (pinned to 1.96.0 by rust-toolchain.toml), Python ≥ 3.11, maturin ≥ 1.7. uv recommended.

uv venv .venv && source .venv/bin/activate
maturin develop                 # build + install the extension in-place
python -c "import pdfspine; print(pdfspine.__version__)"
# redistributable wheel:
maturin build --release         # -> target/wheels/

Building from source needs a C/asm compiler. The bundled pure-Rust PaddleOCR engine depends on tract, which compiles target-specific assembly kernels at build time: a C compiler (cc/clang) on Linux/macOS, or the MSVC Build Tools (incl. ml64.exe) on Windows. Prebuilt wheels (once published) need none of this. To build a fully C-free library, compile the Rust crates with --no-default-features (drops the paddle-ocr feature). Wheels are large (~15–25 MB) because the OCR models (~16 MB) are embedded.

Architecture

A Cargo workspace with a strict dependency DAG; the Python bindings touch exactly one façade crate, and core logic is split into independently testable units.

                  py-bindings   (PyO3 cdylib -> pdfspine._core, abi3-py311)
                       │
                       ▼
                    pdf-api      facade / re-exports
        ┌──────────┬───┴────┬──────────┐
        ▼          ▼        ▼          ▼
    pdf-text   pdf-edit  pdf-image  pdf-render
        │          │        │          │
        └────┬─────┘        │     (fonts, text)
             ▼              │
         pdf-fonts ◄────────┘
             ▼
         pdf-core   ◄────────  pdf-crypto

Crate	Responsibility
pdf-core	object model, lexer/parser, xref, repair, filters, writer, geometry
pdf-crypto	Standard security handler (RC4 / AES-128 / AES-256)
pdf-fonts	font mapping (encodings / ToUnicode / CMap / widths)
pdf-text	content-stream interpreter, get_text, search, find_tables
pdf-edit	page ops, merge, annotations / forms, metadata / TOC, redaction, OCG
pdf-image	image documents, image-XObject codecs, Pixmap
pdf-render	tiny-skia rasterizer → Pixmap, DisplayList, SVG
pdf-api	unified ergonomic façade
py-bindings	PyO3 wrappers → the _core extension module

Develop / test

cargo fmt --all --check
cargo clippy --workspace --all-targets --all-features -- -D warnings
cargo test --workspace
maturin develop && pytest python/tests       # Python tests
python conformance/run_validation.py …       # real-corpus accuracy harness

pdfspine is built strictly test-first (red → green → refactor → harden); the per-function test plan is in docs/test-case-catalog.md.

Documentation

Guide + API reference + PyMuPDF migration guide: build the docs site with mkdocs serve (see mkdocs.yml / docs/). The authoritative design lives in PRD.md.

License

Apache-2.0 — see LICENSE and NOTICE. All third-party dependencies are permissive (MIT / Apache-2.0 / BSD / Zlib / …); the shipped graph is CI-verified free of copyleft.