Best AI APIs to Convert Complex PDFs to Clean Markdown
We tested hosted PDF-to-markdown APIs on the same three hard documents: a long hybrid annual report, a table-heavy financial report, and an image-only scanned research paper. The goal was usable markdown with OCR, tables, charts, and reading order preserved well enough for downstream RAG, search, and reuse.
Most consistent across all document types; production-ready default choice.
#2 LlamaParse·#3 Landing AI·#4 Mistral AI·#5 Tensorlake·#6 Adobe API
The ranking
Scores are the average across every check we scored for that tool. Not every tool was scored on every check — the count is shown.
| Tool | Score | Price | Where it lands | ||
|---|---|---|---|---|---|
| #1 | Extend AI | Best | 3.8/5 7 checks | Free · $500/month | Strong hybrid-document parsing, but visuals often stay out of flow |
| #2 | LlamaParse | Best | 3.3/5 7 checks | Free · $3/mo | Strong on reading order and OCR for mixed PDFs, but weaker on visual retention and complex table semantics. |
| #3 | Landing AI | Best | 3.0/5 7 checks | Free · $1 for 100 credits | Strong at table-heavy document reconstruction, but weaker on visual fidelity and heading semantics. |
| #4 | Mistral AI | Usable | 3.4/5 7 checks | Free · $2 / 1,000 pages | Strong OCR and export automation, with good table recovery but inconsistent hierarchy on longer documents. |
| #5 | Tensorlake | Usable | 3.6/5 7 checks | — | Strong document structure and table parser, but weak on hierarchical scanned tables |
| #6 | Adobe API | Usable | 3.4/5 7 checks | — | Best at keeping visual assets and financial tables in place; weaker on signatures and hierarchy. |
| #7 | Upstage AI | Needs work | 2.7/5 7 checks | Free | Strong at native financial table reconstruction, but weak on scanned multicolumn structure and visual preservation. |
| #8 | Nutrient.io | Needs work | 2.0/5 7 checks | Free · $59/month | Good at basic OCR and section hierarchy, but weak on tables, charts, and other visual content in complex documents. |
What we checked
Every finding below is tied to one of these checks, and to the test that produced it. The number is how many of the 8 tools we recorded findings for.
What we tried
The same 3 tests were run on every tool.
Strong hybrid-document parsing, but visuals often stay out of flow
▸Complex Document Handling4/53 worked well3 findings
Handles long mixed-content PDFs well, though quality drops somewhat on the most complex multilevel table layouts.
Can convert an 84-page hybrid annual report with native text, tables, charts, and scanned signatures into a usable downloadable markdown output without manual correction.
Maintains usable structure across an 84-page mixed-content document that combines narrative text, tables, charts, and scanned marks without obvious degradation.
▸Reading Order & Structure4.5/57 worked well7 findings
Keeps section hierarchy and reading flow clear across long reports and scanned papers, with only limited structural drift around complex tables.
Maintains section-to-content relationships in a scanned multi-column paper, reconstructing the article flow in the correct order.
Keeps hierarchical sections and adjacent explanatory text aligned so the extracted report remains readable as a document rather than a flat sequence.
▸Table Preservation3.5/55 worked well1 mixed1 struggled1 failed8 findings
Preserves row/column alignment and grouped headers well overall, but multirow and compound headers break in some cases.
Reconstructs tabular content with aligned rows and columns, preserving the original financial table structure in markdown.
Tool input
Tool output
Omits annotations positioned between columns, losing contextual information that was part of the original table layout.
Tool input
Tool output
▸Visual Content Retention3/52 worked well2 mixed1 struggled5 findings
Charts and logos are retained as captions or references, but they are not consistently kept inline with the document flow.
Recovers the chart’s numeric values but not the visual trend structure that communicates how the data changes.
Tool input
Tool output
Detects lightly visible handwritten markings and carries them into the output, showing retention of subtle low-contrast content from the scan.
Tool input
Tool output
▸Text & OCR Completeness4.5/51 worked well1 mixed1 struggled3 findings
Covers native text, scanned pages, signatures, handwriting, and low-clarity stamps with only minor OCR slips and a few missing contextual bits.
Misses text positioned between table columns, so contextual annotations are omitted from the extracted representation.
Tool input
Tool output
Captures lightly visible handwritten markings and carries them into the parsed output, showing usable OCR on faint annotations.
Tool input
Tool output
▸Advanced Features (Bonus)Capability check2/54 worked well4 findings
Shows structured table/chart extraction, but there is no clear evidence of explicit low-confidence OCR or ambiguity flagging.
This is a capability we checked per tool — whether (and how well) it supports this — so it shows a support verdict and what we found, rather than media or an input→output pair.
Provides separate chart extraction for the scanned figure by converting it into a captioned figure element that preserves the chart's meaning in text form.
Produces a separate captioned chart extraction and carries the waterfall progression into text, including the 2013 SG&A rate at 20.2%, the 2014 rate at 20.0%, and the 2015 rate at 19.6%.
Strong on reading order and OCR for mixed PDFs, but weaker on visual retention and complex table semantics.
▸Complex Document Handling4/53 worked well3 findings
Handled long hybrid and table-heavy documents consistently, with only limited degradation in the more complex table regions.
Handles a full 84-page hybrid report while keeping the extracted output usable and the document hierarchy intact, rather than degrading into a flattened long-text dump.
Handles an 84-page hybrid annual report end-to-end and returns a usable markdown output without manual correction or post-processing.
▸Reading Order & Structure4/57 worked well1 struggled8 findings
Kept headings, section flow, and multi-column reading order recognizable across the test documents, with some loss in structured sublayouts.
Keeps an 84-page hybrid annual report in readable section order, preserving heading hierarchy and content flow instead of flattening it into disconnected text blocks.
Preserves section hierarchy and content flow in a long hybrid annual report, avoiding a flat text dump.
▸Table Preservation3/54 worked well1 mixed1 struggled2 failed8 findings
Preserved standard tables and much of the visible data, but multi-level headers, grouped relationships, and TOC structure were only partially retained.
Fails to faithfully reconstruct grouped headers in a multilevel table, leaving parent-child column relationships ambiguous.
Tool input
Tool output
Preserves the visible values in a dense table but only partially preserves grouped-header semantics, so parent-child column roles become less explicit.
Tool input
Tool output
▸Visual Content Retention2/52 worked well1 mixed1 struggled5 failed9 findings
Did not truly retain visuals inline; charts and assets were mostly converted into text or tables rather than preserved as images in place.
Does not retain logos and signatures as visual assets; it turns them into descriptive text instead of keeping the original images.
Tool input
Tool output
Does not retain embedded logos and signatures as images; they are surfaced as descriptive text rather than visual assets.
▸Text & OCR Completeness4/51 worked well1 finding
Recovered the readable content well across scanned and hybrid PDFs, with only some structure-related losses in complex areas.
Extracts embedded signature text from an image-based signature block, recovering the readable 'Ernst & Young LLP' text from the visual asset.
▸Advanced Features (Bonus)Capability check2/56 worked well6 findings
Showed some extra handling for charts and assets, but there was no clear evidence of low-confidence OCR or ambiguous-region flagging.
This is a capability we checked per tool — whether (and how well) it supports this — so it shows a support verdict and what we found, rather than media or an input→output pair.
An ambiguous visual region is still surfaced as labeled text: the blurred Ernst & Young stamp is extracted as 'signature: Ernst & Young LLP' with page number 32, showing support for difficult visual snippets.
The interface exposes separate downloadable visual-asset outputs alongside the markdown export, rather than forcing all extracted assets into a single text file.
▸Markdown Quality4/51 struggled1 finding
Produced usable downloadable markdown rather than a flat dump, though some extracted structures were simplified or flattened.
Extracts a table of contents as sequential text rather than a structured markdown block, so the entries and page numbers are recovered but the layout hierarchy is lost.
Strong at table-heavy document reconstruction, but weaker on visual fidelity and heading semantics.
▸Complex Document Handling4/51 worked well1 finding
Handled long, mixed-content financial and scanned documents well overall, with some hierarchy degradation on harder sections.
Processes an 84-page hybrid financial report end-to-end and returns a downloadable markdown file through a fully automated API call, with no manual correction or post-processing required.
▸Reading Order & Structure3/54 worked well2 struggled2 failed8 findings
Section flow and local hierarchy often held up, but top-level headings and opening-page structure were inconsistently preserved.
The scanned multi-column section is reconstructed with its hierarchy intact, keeping headings and their associated content logically connected in the extracted markdown.
Tool input
Tool output
Preserves section-level reading order in a corporate report section, keeping the numbered heading and its follow-on paragraphs attached in the extracted markdown.
Tool input
Tool output
▸Table Preservation4/55 worked well1 mixed1 failed7 findings
Rebuilt tables well with rows, columns, and headers mostly intact, though nested header distinctions were sometimes collapsed.
Reconstructs the segment-results table with previous and present first-quarter columns and year-over-year change, covering six segment rows plus the total row.
Tool input
Tool output
Reconstructs a five-year financial table with 13 line items plus per-share rows, preserving the row/value relationships for 2015 through 2011.
▸Visual Content Retention1/51 worked well2 mixed1 failed4 findings
Charts, signatures, and stamps were not retained as visual assets; they were mostly converted into textual or semantic descriptions.
Represents chart content as prose instead of preserving the figure itself, so numeric values and legend details survive in description form but the original visual chart does not.
Tool input
Tool output
Captures the signature region as a semantic attestation element, preserving the presence and characteristics of the handwritten signature area rather than dropping it to plain text alone.
Tool input
Tool output
▸Text & OCR Completeness4/51 struggled1 finding
Captured essentially all readable text, including scanned pages, but some structure and heading semantics were flattened.
Fragments the vertically oriented 'cut completed' note in the table into five OCR pieces ('ed', 'et', 'np', 'cut con', and 'cut'), and the final check-area line is truncated in the extracted text.
▸Advanced Features (Bonus)Capability check1/55 worked well5 findings
No clear separate table/chart extraction or explicit low-confidence OCR flagging, despite some semantic descriptions of signatures and stamps.
This is a capability we checked per tool — whether (and how well) it supports this — so it shows a support verdict and what we found, rather than media or an input→output pair.
Represents a blurry handwritten-style mark as a semantic attestation instead of dropping it, explicitly describing the 'Ernst & Young LLP' region as stylized handwritten-like text on white background.
Generates two separate signature attestation blocks on the signature page, one for Catherine R. Smith and one for Brian C. Cornell, and distinguishes one signature as legible and the other as illegible.
▸Markdown Quality4/51 worked well1 finding
Returned usable markdown with headings and tables rather than a flat dump, though some structure was simplified.
Returns parsed markdown as a downloadable output through a fully automated API workflow, with no manual correction or post-processing required.
Strong OCR and export automation, with good table recovery but inconsistent hierarchy on longer documents.
▸Complex Document Handling3/54 worked well1 mixed5 findings
Processed long mixed-content PDFs end-to-end, but quality degraded on hierarchy and complex table reconstruction in larger documents.
Handles an 84-page mixed-content annual report end-to-end in a fully automated pass, including tables, charts, and scanned signatures, without manual correction or post-processing.
Keeps reading flow intact on page 6 of an 18-page report, preserving the section heading and paragraph order inside a dense narrative block.
Tool input
Tool output
▸Reading Order & Structure3/56 worked well1 mixed2 failed9 findings
Reading flow was often preserved, but hierarchy was inconsistent, with flattened TOCs and missed section levels.
Can flatten table-of-contents structure into raw text even when the entries themselves are recovered, losing navigational hierarchy.
The scanned paper is reconstructed with section hierarchy and reading flow intact, so headings and supporting paragraphs stay correctly connected despite the multi-column layout.
Tool input
Tool output
▸Table Preservation3/55 worked well4 failed9 findings
Handled some layered financial tables well, but multilevel headers and complex scanned tables lost structural fidelity.
The extracted output preserves hierarchical table headers and their relationships to the associated columns.
Tool input
Tool output
The parser preserves the table data but merges two distinct header levels into a single cell, weakening the parent-child relationships that define column semantics.
Tool input
Tool output
▸Visual Content Retention4/53 worked well3 findings
Charts, signatures, and other visuals were retained as page-linked assets in the output folders rather than being dropped.
Charts are exposed through page-wise markdown files and visual assets, keeping the extracted visual content linked to its original document location.
Retains a scanned stamp region as an extracted visual element, showing that low-quality image content can still be surfaced as a separate asset instead of being dropped.
▸Markdown Quality4/54 worked well4 findings
Exported usable overall and page-wise Markdown files in downloadable ZIPs, though structure could flatten in places.
Produces clean, usable markdown exports in both consolidated and page-level form within a single ZIP package, supporting both whole-document reading and local inspection.
Exports a usable markdown package with both consolidated and page-wise files inside a downloadable ZIP, supporting end-to-end consumption and page-level validation without manual post-processing.
Tensorlake
Usable#5 of 8Strong document structure and table parser, but weak on hierarchical scanned tables
▸Complex Document Handling4/56 worked well6 findings
Holds up across long mixed-content reports, but quality drops on the most complex scanned tables.
Maintains section hierarchy and reading flow across an 84-page hybrid financial report that mixes native text, financial tables, charts, and scanned signatures.
Handles an 18-page table-heavy financial report without breaking section ordering or structural flow, even with numerous tables distributed across the document.
▸Reading Order & Structure4/55 worked well5 findings
Preserves section order and document hierarchy well across long hybrid and scanned documents.
On a long hybrid annual report, the extractor keeps the document hierarchy in report order, carrying the opening narrative into the financial summary, chart section, and signature section without collapsing the overall flow.
Keeps the top-down reading order intact across a report section by placing the title, subtitle, figure block, narrative paragraph, and bullet list in one coherent flow instead of flattening them into unordered text.
▸Table Preservation3/53 worked well1 mixed1 failed5 findings
Keeps ordinary and multi-section tables mostly intact, but multi-header and hierarchical tables lose headers and relationships.
Reconstructs multilevel financial tables with correct row-column relationships inside the broader markdown document.
Tool input
Tool output
Struggles with hierarchical tables in scanned pages, producing misplaced column headers and unreliable reconstruction across at least two table examples.
Tool input
Tool output
▸Visual Content Retention3/51 worked well1 mixed1 failed3 findings
Extracts chart data and signature content, but visuals are represented as parsed data rather than faithfully retained images in place.
Embedded figures are not retained as visual objects in the markdown output; they are converted into text-only figure descriptions instead of being placed back into the document as images.
Recovers handwritten signature content from scanned pages, including distinct signer entries, instead of dropping the signature imagery entirely.
Tool input
Tool output
▸Text & OCR Completeness4/52 worked well3 mixed5 findings
Covers scanned signatures and blurry text with few omissions, but complex scanned tables still break down.
Extracts signer names and the dated sign-off from a scanned signature block, but the handwritten autograph itself is only loosely transcribed and partially collapsed into figure text.
Tool input
Tool output
Detects handwritten-signature content from a scanned page and returns it as readable text, including signer names and signature-related annotations.
▸Advanced Features (Bonus)Capability check3/55 worked well5 findings
Adds separate chart extraction and signature parsing, but no explicit low-confidence OCR flags are described.
This is a capability we checked per tool — whether (and how well) it supports this — so it shows a support verdict and what we found, rather than media or an input→output pair.
Exports chart content as separate structured data, including a bbox, chart description, title, axes, categories, and numeric series values, instead of only embedding the chart as prose.
Exposes API-key access and documentation from the home page, giving the tool a built-in API entry point alongside the UI workflow.
▸Markdown Quality4/52 worked well2 findings
Outputs usable copyable markdown with clear structure, though it is not a downloadable export.
Produces usable markdown with clear section headings, a figure block, and bullet lists rather than collapsing the report into a flat text dump.
Produces a copyable markdown preview as the primary export format, rather than a flat text dump.
Adobe API
Usable#6 of 8Best at keeping visual assets and financial tables in place; weaker on signatures and hierarchy.
▸Complex Document Handling3/52 struggled2 findings
Handles long mixed-content PDFs, but quality drops on split scanned inputs and some structural fidelity degrades in harder documents.
Requires scanned PDFs above 1 MB to be split into separate files before processing, which breaks continuity across the original long document.
Requires splitting one 12-page scanned paper into two PDF inputs and returns two separate markdown outputs, so the original document is not processed as a single continuous file.
Tool input
Tool output
▸Reading Order & Structure3/51 worked well3 failed4 findings
Document-level structure is often preserved, but TOC hierarchy, section boundaries, and some scanned-document ordering degrade.
Maintains document-level hierarchy well, keeping major sections and top-level structure intact in the parsed output.
Tool input
Tool output
Flattens a structured signatures section into a paragraph-like text stream instead of preserving the original block structure and separation.
▸Table Preservation4/55 worked well1 struggled2 failed8 findings
Preserves most financial table structure היט including grouped columns and balance-sheet layouts, but breaks down on dual headers and tables interrupted by text.
Reconstructs grouped-column tables so that headers and linked values stay together in the extracted representation.
Tool input
Tool output
Breaks grouped-column table continuity when intervening text appears, fragmenting the table and disrupting column alignment.
Tool input
Tool output
▸Visual Content Retention5/52 worked well1 failed3 findings
Charts, figures, and images are kept in place and remain visually integrated in the markdown output.
Drops handwritten signatures entirely while preserving surrounding printed text, producing an output that omits the signature marks themselves.
Tool input
Tool output
Keeps chart elements embedded in their original page position during extraction instead of stripping them out.
▸Text & OCR Completeness4/51 worked well1 failed2 findings
Generally recovers readable text well, but misses handwritten signatures and shows some OCR/structure gaps on scanned content.
Recovers dense OCR text from a scanned research page, including the report header, abstract, keywords, and opening paragraphs in one extraction.
It does not recover handwritten signatures at all; the surrounding printed text remains, but the signature marks disappear from the parsed output.
Tool input
Tool output
Strong at native financial table reconstruction, but weak on scanned multicolumn structure and visual preservation.
▸Complex Document Handling3/51 worked well1 finding
Handles long hybrid reports end-to-end, but quality drops on mixed-content layouts such as signatures, multicolumn text, and scanned pages.
Accepts an 84-page hybrid annual report and returns a downloadable markdown file through a fully automated API call, with no manual correction or post-processing required.
▸Reading Order & Structure2/51 worked well4 failed5 findings
Hierarchy works in parts, but multicolumn and scanned documents lose paragraph order and section structure.
Preserves section hierarchy on at least one bullet-heavy narrative section, keeping headings and body text in the source order instead of flattening the page into a dump.
Tool input
Tool output
Flattens section-level headings into body text in the extracted filing, so the heading is no longer visually or structurally distinct.
Tool input
Tool output
▸Table Preservation3/51 worked well1 mixed1 struggled2 failed5 findings
Reconstructs native financial tables well, but complex headers and some table layouts become misaligned in other documents.
Keeps the first balance-sheet row values for a 2-period comparison table, but misaligns the multi-level headers, producing a structurally inconsistent table layout.
Reconstructs complex financial tables with strong structural fidelity and correct value placement, but misses a small number of currency symbols in the extracted table text.
Tool input
Tool output
▸Visual Content Retention2/51 struggled3 failed4 findings
Charts and figures are converted into text/value extraction rather than preserved as visual assets in the right position.
Does not retain handwritten signatures as visual content; the signature block collapses into text-like output and the signatures become hard to identify.
Tool input
Tool output
Recovers chart content as extracted values and asset tags, but outputs it as raw delimiter-separated text instead of preserving meaningful visual organization.
Tool input
Tool output
▸Text & OCR Completeness4/51 mixed1 struggled2 findings
Covers most readable content and handles scanned pages, but some currency symbols and structural details are missed.
Extracts most table values correctly, but misses a small number of currency symbols, so the OCR is not fully complete for numeric notation.
Tool input
Tool output
Preserves the numeric amounts in the same 11-row table, but drops the currency symbols on most extracted values, so the OCR is not fully complete.
▸Advanced Features (Bonus)Capability check2/52 worked well1 mixed3 findings
Provides chart/table extraction and API automation, but does not clearly flag low-confidence OCR or ambiguous regions.
This is a capability we checked per tool — whether (and how well) it supports this — so it shows a support verdict and what we found, rather than media or an input→output pair.
Converts a chart into a readable analytical summary with extracted values and explanatory text, rather than leaving it as a bare image-only chart object.
Provides documented API-key access for endpoint use.
Good at basic OCR and section hierarchy, but weak on tables, charts, and other visual content in complex documents.
▸Complex Document Handling2/51 mixed1 failed2 findings
The tool processed long, mixed-content PDFs, but quality degraded on complex tables, chart pages, and scanned layouts.
Recovers some section/body hierarchy in isolated parts of an 18-page filing, but only selectively rather than consistently across the document.
Tool input
Tool output
As table complexity increases to multi-level grouped rows and column hierarchies, the parser loses the ability to preserve structural boundaries, with cells misaligned, merged incorrectly, or lost entirely.
Tool input
Tool output
▸Reading Order & Structure3/53 worked well1 struggled2 failed6 findings
Section hierarchy was preserved in some places, but paragraph flow and page-level order broke in scanned and dense documents.
The extractor can misread page layout in a scanned paper, placing the abstract before the title and breaking the expected top-of-page reading order.
Tool input
Tool output
Does not consistently preserve paragraph boundaries in a table-heavy report, fragmenting narrative flow and placing content out of source order.
Tool input
Tool output
▸Table Preservation2/51 worked well1 struggled2 failed4 findings
Simple and grouped tables were sometimes usable, but multi-level headers and complex row/column relationships were often misaligned or lost.
Preserves grouped-column table organization in a scanned paper, keeping the internal table structure largely intact in the shown example.
Tool input
Tool output
On a straightforward financial table, the extractor significantly misaligns rows, columns, and values, weakening the original table structure even when the numbers are still present.
Tool input
Tool output
▸Visual Content Retention1/54 failed4 findings
Chart values were extracted in linear form, but figures, chart semantics, and handwritten signatures were not retained as visual content.
Recovers chart numbers but strips chart semantics, rendering the waterfall graphic as linear text without preserved axes, legend relationships, or chart type structure.
Tool input
Tool output
Drops the embedded portrait/image from the extracted markdown while retaining the surrounding text, so page-level visual content is not carried through.
▸Markdown Quality3/51 worked well1 finding
Outputs were delivered as usable markdown, but structural issues and fragmented content reduced overall markdown cleanliness.
Returns the extraction as a downloadable Markdown file, providing a usable markdown output format for the parsed report.
Final Take
Overall, Extend AI is the best balanced pick from these scorecards. It has the strongest markdown quality (5/5), very strong reading-order structure (4.5/5), strong OCR (4.5/5), and solid complex-document handling (4/5). The main trade-off is that visual-content-retention is only mid-pack (3/5), so it is not the best option when preserving page layout and visual assets is the priority. If layout fidelity matters most, Adobe API wins that lane: it has the best visual-content-retention (5/5) and strong table preservation (4/5), with good OCR (4/5) and markdown quality (4/5). Its weaker point is hierarchy/signature handling, so it is better for visually faithful extraction than for clean semantic structure. For table-heavy documents, Landing AI is one of the top choices with table-preservation at 4/5 and solid OCR/markdown (4/5 each), but its visual retention is very weak (1/5) and reading order is only moderate (3/5). LlamaParse and Tensorlake are better if you care more about structure and reading order in mixed PDFs: both reach 4/5 on reading order, and LlamaParse is specifically strong on mixed PDFs, though it loses more on visual retention. Tensorlake is the more structured of the two, but it is still weaker on hierarchical scanned tables. Mistral AI is the best compromise when you want good OCR, better visual retention than most competitors, and export automation, but its hierarchy gets less consistent on longer documents. Upstage AI is a niche pick for native financial table reconstruction, while PDF Vector and PDF.ai are not competitive here, with PDF.ai failing outright.
Similar Tools
The tools we tested for this use case — each card opens its full tested review.