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.
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 | Where it lands | ||
|---|---|---|---|---|
| #1 | Extend AI | Best | 3.8/5 7 checks | Strong hybrid-document parsing, but visuals often stay out of flow |
| #2 | LlamaParse | Best | 3.3/5 7 checks | 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 | Strong at table-heavy document reconstruction, but weaker on visual fidelity and heading semantics. |
| #4 | Mistral AI | Usable | 3.4/5 7 checks | 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 | 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 | 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
How it scored
Complex Document Handling4/5Reading Order & Structure4.5/5Table Preservation3.5/5Visual Content Retention3/5Text & OCR Completeness4.5/5Advanced Features (Bonus)2/5▸Complex Document Handling4/53 worked well3 findings
Handles long mixed-content PDFs well, though quality drops somewhat on the most complex multilevel table layouts.
Handles an 84-page mixed-content financial report end to end in a single automated markdown export, keeping the converted document usable as a coherent report rather than degrading across sections.
Maintains usable structure across an 84-page mixed-content document that combines narrative text, tables, charts, and scanned marks without obvious degradation.
▸Reading Order & Structure4.5/517 worked well17 findings
Keeps section hierarchy and reading flow clear across long reports and scanned papers, with only limited structural drift around complex tables.
Keeps section hierarchy and explanatory flow intact in an 84-page hybrid annual report, so the markdown remains readable as a report rather than a flat text dump.
Maintains report hierarchy and reading flow across an 84-page hybrid annual report, keeping headings, narrative paragraphs, and bullets in a coherent markdown structure instead of flattening the document.
▸Table Preservation3.5/513 worked well2 mixed8 struggled4 failed27 findings
Preserves row/column alignment and grouped headers well overall, but multirow and compound headers break in some cases.
Preserves grouped-column hierarchy in multilevel tables, carrying header and subheader relationships into the extracted markdown.
Reconstructs tabular content with aligned rows and columns, preserving the original financial table structure in markdown.
▸Visual Content Retention3/55 worked well10 mixed3 struggled18 findings
Charts and logos are retained as captions or references, but they are not consistently kept inline with the document flow.
Retains chart meaning by converting a waterfall graphic into a captioned structured element that explains the visual progression in text.
Detects lightly visible handwritten markings and carries them into the output, showing retention of subtle low-contrast content from the scan.
▸Text & OCR Completeness4.5/52 worked well6 mixed3 struggled11 findings
Covers native text, scanned pages, signatures, handwriting, and low-clarity stamps with only minor OCR slips and a few missing contextual bits.
Captures lightly visible handwritten or marked content and carries it into the extracted representation.
Extracts low-clarity signature and stamp text, but can introduce small OCR errors such as reading 'LLP' as '1LP'.
▸Advanced Features (Bonus)2/514 worked well14 findings
Shows structured table/chart extraction, but there is no clear evidence of explicit low-confidence OCR or ambiguity flagging.
Provides separate chart extraction by turning chart content into a captioned figure element that preserves the chart's meaning beyond the visual encoding.
Adds a caption element for chart extraction, turning the chart into structured text while keeping the numeric relationships legible.
Strong on reading order and OCR for mixed PDFs, but weaker on visual retention and complex table semantics.
How it scored
Complex Document Handling4/5Reading Order & Structure4/5Table Preservation3/5Visual Content Retention2/5Text & OCR Completeness4/5Advanced Features (Bonus)2/5Markdown Quality4/5▸Complex Document Handling4/55 worked well5 findings
Handled long hybrid and table-heavy documents consistently, with only limited degradation in the more complex table regions.
Handles an 84-page hybrid annual report end-to-end and returns a usable markdown output without manual correction or post-processing.
Handles an 84-page mixed-content annual report end-to-end and returns a usable markdown export without manual correction or post-processing.
▸Reading Order & Structure4/525 worked well3 struggled2 failed30 findings
Kept headings, section flow, and multi-column reading order recognizable across the test documents, with some loss in structured sublayouts.
Reconstructs a scanned multi-column paper into a coherent reading flow, keeping section headings attached to the paragraphs that follow.
Preserves section hierarchy and overall content flow in a multi-column annual report instead of breaking the page into disconnected reading fragments.
▸Table Preservation3/527 worked well4 mixed12 struggled6 failed49 findings
Preserved standard tables and much of the visible data, but multi-level headers, grouped relationships, and TOC structure were only partially retained.
For a complex grouped-header table, the output keeps the visible values but weakens parent-child column relationships, making the structure less explicit.
Retains a standard financial table’s row alignment, column organization, and value associations in the markdown output.
▸Visual Content Retention2/53 worked well1 mixed3 struggled12 failed19 findings
Did not truly retain visuals inline; charts and assets were mostly converted into text or tables rather than preserved as images in place.
Converts a chart into a structured table while preserving legend-to-value mapping, so the underlying data relationships remain intact.
Does not retain charts as charts; the chart is converted into a structured table even though legend-to-value mapping survives.
▸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)2/514 worked well14 findings
Showed some extra handling for charts and assets, but there was no clear evidence of low-confidence OCR or ambiguous-region flagging.
Provides separate chart extraction by converting a 9-step SG&A waterfall chart into a compact parsed table that retains the three SG&A rate points (20.2%, 20.0%, 19.6%) and the intermediate component deltas.
Provides separate chart extraction by turning a mortality bar chart into a structured table with 3 years of values across 5 categories, while retaining the legend-to-value mapping.
▸Markdown Quality4/52 struggled2 findings
Produced usable downloadable markdown rather than a flat dump, though some extracted structures were simplified or flattened.
Extracts the table of contents as sequential text rather than a structured TOC, so entries and page numbers are recovered but the TOC’s organization is lost.
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.
How it scored
Complex Document Handling4/5Reading Order & Structure3/5Table Preservation4/5Visual Content Retention1/5Text & OCR Completeness4/5Advanced Features (Bonus)1/5Markdown Quality4/5▸Complex Document Handling4/54 worked well4 findings
Handled long, mixed-content financial and scanned documents well overall, with some hierarchy degradation on harder sections.
Processes an 84-page hybrid report with tables, charts, and scanned signatures in one automated pass, producing usable markdown without manual correction.
Handles an 84-page hybrid financial report containing tables, charts, and scanned signatures, returning usable markdown without manual correction.
▸Reading Order & Structure3/522 worked well1 mixed3 struggled17 failed43 findings
Section flow and local hierarchy often held up, but top-level headings and opening-page structure were inconsistently preserved.
Flattens the document's highest-level heading into plain text instead of an H1, which weakens the reconstructed hierarchy even though the content is retained.
The highest-level heading is flattened into plain text instead of being preserved as an H1, which weakens the reconstructed document hierarchy.
▸Table Preservation4/522 worked well3 mixed1 struggled7 failed33 findings
Rebuilt tables well with rows, columns, and headers mostly intact, though nested header distinctions were sometimes collapsed.
Reconstructs a financial table in markdown with its header row, row labels, and numeric columns aligned to the source layout.
Successfully reconstructs a multilevel financial table in markdown, preserving header relationships, row alignment, and column organization.
▸Visual Content Retention1/51 worked well6 mixed1 struggled8 failed16 findings
Charts, signatures, and stamps were not retained as visual assets; they were mostly converted into textual or semantic descriptions.
Replaces a chart with descriptive text that carries numeric values and legend details, but does not retain the chart as a visual figure.
Does not retain the waterfall chart as a visual asset; it converts the chart into a text description of values and increase/decrease relationships instead.
▸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)1/519 worked well19 findings
No clear separate table/chart extraction or explicit low-confidence OCR flagging, despite some semantic descriptions of signatures and stamps.
Represents the blurred "Ernst & Young" marker with a generated description, preserving an ambiguous low-visibility region semantically instead of omitting it.
The signature region is captured as a semantic attestation element, preserving the presence and characteristics of the handwritten signature instead of only extracting the signer name.
▸Markdown Quality4/52 worked well2 findings
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.
Returns the extraction as downloadable Markdown output across runs, rather than only as an in-app preview.
Strong OCR and export automation, with good table recovery but inconsistent hierarchy on longer documents.
How it scored
Complex Document Handling3/5Reading Order & Structure3/5Table Preservation3/5Visual Content Retention4/5▸Complex Document Handling3/55 worked well1 mixed6 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.
Supports dual output organization for a long report by creating separate page-level files alongside a consolidated markdown document, which scales localized validation across the document.
▸Reading Order & Structure3/519 worked well1 mixed4 struggled16 failed40 findings
Reading flow was often preserved, but hierarchy was inconsistent, with flattened TOCs and missed section levels.
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.
The table of contents entries remain present, but the navigational hierarchy is flattened into raw text, so the original TOC organization is not preserved.
▸Table Preservation3/522 worked well1 mixed2 struggled15 failed40 findings
Handled some layered financial tables well, but multilevel headers and complex scanned tables lost structural fidelity.
Reconstructs a 5-year financial results table into a usable markdown table, keeping year columns and row-to-value relationships intact.
Preserves layered financial tables in a usable structured form, keeping header, row, and value relationships aligned rather than collapsing the table into plain text.
▸Visual Content Retention4/515 worked well15 findings
Charts, signatures, and other visuals were retained as page-linked assets in the output folders rather than being dropped.
The parser exposes charts through page-wise markdown files and visual assets, keeping the extracted visual content linked to its original document location.
The parser extracts visual assets into page-specific output folders so charts, signatures, and other elements remain associated with their source pages instead of being collapsed into one output block.
▸Markdown Quality4/55 worked well5 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.
Returns usable markdown as a downloadable export, including both page-level files and a consolidated document packaged together for downstream inspection.
Tensorlake
Usable#5 of 8Strong document structure and table parser, but weak on hierarchical scanned tables
How it scored
Complex Document Handling4/5Reading Order & Structure4/5Table Preservation3/5Visual Content Retention3/5Text & OCR Completeness4/5Advanced Features (Bonus)3/5Markdown Quality4/5▸Complex Document Handling4/56 worked well6 findings
Holds up across long mixed-content reports, but quality drops on the most complex scanned tables.
Handles an 18-page table-heavy financial report without breaking section ordering or structural flow, even with numerous tables distributed across the document.
Handles an 84-page mixed-content report while keeping heading order and section relationships aligned across tables, charts, and scanned signatures.
▸Reading Order & Structure4/521 worked well21 findings
Preserves section order and document hierarchy well across long hybrid and scanned documents.
Preserves document hierarchy and heading order so the extracted flow stays close to the source layout.
Preserves heading order and section relationships in an 84-page financial report, keeping the extracted hierarchy closely aligned with the source layout.
▸Table Preservation3/514 worked well1 mixed2 struggled12 failed29 findings
Keeps ordinary and multi-section tables mostly intact, but multi-header and hierarchical tables lose headers and relationships.
Fails on multi-header tables by not inferring the header hierarchy and omitting at least one header label, which yields an incomplete reconstruction.
Reconstructs financial tables with row, column, and value relationships intact, keeping the table structure structurally faithful in markdown.
▸Visual Content Retention3/52 worked well1 mixed1 failed4 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.
▸Text & OCR Completeness4/53 worked well10 mixed13 findings
Covers scanned signatures and blurry text with few omissions, but complex scanned tables still break down.
Recovers degraded stamp text well enough to capture the Ernst & Young reference, but makes a symbol-level OCR error by rendering the ampersand as a plus sign.
The parser can read degraded stamp text, including the Ernst & Young reference, but it introduces a one-symbol OCR error by rendering an ampersand as a plus sign.
▸Advanced Features (Bonus)3/516 worked well16 findings
Adds separate chart extraction and signature parsing, but no explicit low-confidence OCR flags are described.
Extracts chart values into a separate tabular representation without requiring a dedicated chart-processing mode, showing an extra structured extraction path.
Exposes API-key access and documentation from the home page, giving the tool a built-in API entry point alongside the UI workflow.
▸Markdown Quality4/53 worked well3 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.
Outputs usable markdown rather than a flat text dump, with section headings, table blocks, chart blocks, and signature text separated into readable markdown structure.
Adobe API
Usable#6 of 8Best at keeping visual assets and financial tables in place; weaker on signatures and hierarchy.
How it scored
Complex Document Handling3/5Reading Order & Structure3/5Table Preservation4/5Visual Content Retention5/5Text & OCR Completeness4/5▸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.
▸Reading Order & Structure3/57 worked well14 failed21 findings
Document-level structure is often preserved, but TOC hierarchy, section boundaries, and some scanned-document ordering degrade.
Preserves section headings and subsection flow in a narrative financial section, keeping the main title, numbered subsection, and body text in order.
Section boundaries and document hierarchy are not preserved in scanned content; the title page is output without structural cues or organizational separation.
▸Table Preservation4/534 worked well3 mixed3 struggled12 failed52 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.
Does not distinguish row headers from column headers in dual-header tables, flattening header roles and weakening the table's structure.
Preserves compact multi-column table hierarchy and keeps header-value relationships intact in grouped tables.
▸Visual Content Retention5/516 worked well8 failed24 findings
Charts, figures, and images are kept in place and remain visually integrated in the markdown output.
Preserves charts and images as integrated assets in the output layout instead of detaching them from the surrounding document flow.
Keeps chart elements embedded in situ and in their original position within the extracted document flow.
▸Text & OCR Completeness4/51 worked well2 failed3 findings
Generally recovers readable text well, but misses handwritten signatures and shows some OCR/structure gaps on scanned content.
Fails to recover handwritten signature content while still retaining the surrounding printed text, leaving the signature area incomplete.
It does not recover handwritten signatures at all; the surrounding printed text remains, but the signature marks disappear from the parsed output.
Strong at native financial table reconstruction, but weak on scanned multicolumn structure and visual preservation.
How it scored
Complex Document Handling3/5Reading Order & Structure2/5Table Preservation3/5Visual Content Retention2/5Text & OCR Completeness4/5Advanced Features (Bonus)2/5▸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 & Structure2/57 worked well25 failed32 findings
Hierarchy works in parts, but multicolumn and scanned documents lose paragraph order and section structure.
In multicolumn narratives, headings become misaligned and the reading path diverges significantly from the source layout.
Loses the reading order on a dense scanned two-column page, flattening the document flow so the original section sequencing is not maintained.
▸Table Preservation3/54 worked well12 mixed4 struggled7 failed27 findings
Reconstructs native financial tables well, but complex headers and some table layouts become misaligned in other documents.
Misaligns multi-row table headers with their data regions in complex grouped tables, producing an inconsistent table structure.
Reconstructs a dense financial table with strong structural fidelity and correct value placement across columns.
▸Visual Content Retention2/53 mixed4 struggled12 failed19 findings
Charts and figures are converted into text/value extraction rather than preserved as visual assets in the right position.
Does not retain a waterfall chart as a visual object; it replaces the chart with a text-first analytical summary and extracted values instead of preserving the graphic in place.
Transforms a waterfall chart into a text-based analytical summary with extracted values and explanation, but does not retain the chart as a visual figure.
▸Text & OCR Completeness4/52 mixed1 struggled3 findings
Covers most readable content and handles scanned pages, but some currency symbols and structural details are missed.
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.
In reconstructed tables, it misses a small number of currency symbols, so the numeric text is not fully complete.
▸Advanced Features (Bonus)2/53 worked well3 mixed6 findings
Provides chart/table extraction and API automation, but does not clearly flag low-confidence OCR or ambiguous regions.
Recovers a figure through value extraction and asset tagging, but emits raw delimiter-separated text instead of an interpretable chart or figure representation.
Extracts chart values and tags the asset, but emits them as raw delimiter-separated text rather than an organized chart representation.
Good at basic OCR and section hierarchy, but weak on tables, charts, and other visual content in complex documents.
How it scored
Complex Document Handling2/5Reading Order & Structure3/5Table Preservation2/5Visual Content Retention1/5▸Complex Document Handling2/51 mixed2 failed3 findings
The tool processed long, mixed-content PDFs, but quality degraded on complex tables, chart pages, and scanned layouts.
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.
Recovers some section/body hierarchy in isolated parts of an 18-page filing, but only selectively rather than consistently across the document.
▸Reading Order & Structure3/518 worked well4 struggled10 failed32 findings
Section hierarchy was preserved in some places, but paragraph flow and page-level order broke in scanned and dense documents.
Preserves hierarchical reading order in a scanned research paper, correctly aligning section headings with the corresponding column content.
The extractor correctly aligns section headings with their corresponding column content in a multi-column scanned layout, preserving local reading order and hierarchy.
▸Table Preservation2/57 worked well7 struggled16 failed30 findings
Simple and grouped tables were sometimes usable, but multi-level headers and complex row/column relationships were often misaligned or lost.
Struggles to preserve a standard financial table's row-and-column structure, with significant misalignment that weakens relationships between cells and values.
The tool loses portions of a multi-level table header, so parent-child column relationships are not reconstructed as they appear in the source document.
▸Visual Content Retention1/57 mixed7 struggled13 failed27 findings
Chart values were extracted in linear form, but figures, chart semantics, and handwritten signatures were not retained as visual content.
The extractor can recover chart values, but it corrupts the chart’s layout and does not preserve the original structured relationships, so the graphic is not retained as a chart.
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
More tools like the ones we tested here — each links to its own tested review.