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 | Pay-as-you-go | 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 Handling4/54 worked well4 findings
Handles long mixed-content PDFs well, though quality drops somewhat on the most complex multilevel table layouts.
Handles 84-page mixed-content reports end to end in a single automated markdown export, keeping them usable and structured across narrative text, tables, charts, and scanned signatures/marks without obvious degradation or manual correction.
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.
▸Reading Order & Structure4.5/58 worked well8 findings
Keeps section hierarchy and reading flow clear across long reports and scanned papers, with only limited structural drift around complex tables.
Consistently preserved section hierarchy, heading-to-content relationships, and narrative flow, keeping reports and scanned multi-column papers readable rather than flattening them.
Maintains report hierarchy and narrative flow so a section title, paragraph text, and a four-item bullet list stay in readable order instead of collapsing into a flat text dump.
▸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.
Preserves row-column relationships and grouping cues in a complex table, producing a structured reconstruction rather than a flat transcription.
Tool input
Tool output
Reconstructs complex financial tables with aligned rows and columns, preserving the table's original structure in markdown.
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.
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
Preserves visual assets through detached references and annotations, but does not keep them inline at their original reading position.
▸Text & OCR Completeness4.5/51 worked well2 mixed1 struggled4 findings
Covers native text, scanned pages, signatures, handwriting, and low-clarity stamps with only minor OCR slips and a few missing contextual bits.
It captured faint handwritten, signature, and stamp text, but missed text between table columns and introduced a one-character OCR error, so completeness was uneven.
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.
Exposes API-key generation in the developer area alongside documentation support, enabling programmatic use without manual post-processing.
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 Handling4/54 worked well4 findings
Handled long hybrid and table-heavy documents consistently, with only limited degradation in the more complex table regions.
It consistently handled the 84-page mixed-content/hybrid annual report end-to-end, keeping the output usable and the document hierarchy intact without manual correction or post-processing.
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.
▸Reading Order & Structure4/57 worked well1 mixed1 struggled9 findings
Kept headings, section flow, and multi-column reading order recognizable across the test documents, with some loss in structured sublayouts.
It generally preserves reading order and section hierarchy across reports and scanned pages, but the table of contents is only recovered as sequential text and loses hierarchical relationships.
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.
▸Table Preservation3/54 worked well2 mixed1 struggled2 failed9 findings
Preserved standard tables and much of the visible data, but multi-level headers, grouped relationships, and TOC structure were only partially retained.
It often preserves row alignment, column organization, and grouped-header relationships, but complex grouped-header tables can become less explicit and the table of contents is only extracted as sequential text.
Preserves a scanned research table’s multi-level column organization and grouped-header relationships in the extracted output.
Tool input
Tool output
▸Visual Content Retention2/52 worked well2 mixed1 struggled5 failed10 findings
Did not truly retain visuals inline; charts and assets were mostly converted into text or tables rather than preserved as images in place.
It preserves the underlying content of some visuals by turning charts into structured tables with readable legend-to-value mapping, but it generally does not keep non-text visuals as visual assets: logos, signatures, stamps, portraits, and other images are surfaced as descriptive text or omitted inline.
A page that includes a left-side portrait image is returned as text-only blocks: the title, author line, paragraph text, and bullets are preserved, but the image itself is not retained inline.
Tool input
Tool output
▸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.
The settings UI includes API key administration with a 'Generate New Key' control and 2 listed project API keys, showing built-in key management for authenticated use.
Provides API-key creation together with documentation support.
▸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 well1 mixed2 struggled2 failed9 findings
Section flow and local hierarchy often held up, but top-level headings and opening-page structure were inconsistently preserved.
It usually preserved reading order and section hierarchy, keeping headings, paragraphs, bullets, and multi-column content in sequence, but it was weaker on opening-page/title-page structure and sometimes flattened or misordered heading semantics.
Flattens the top-level heading semantics on the same page: the main title is recovered as plain text rather than an H1-style heading, reducing hierarchy fidelity.
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
Preserves nested table structure and values in a scanned document, including multi-level layouts.
Tool input
Tool output
▸Visual Content Retention1/51 worked well3 mixed1 failed5 findings
Charts, signatures, and stamps were not retained as visual assets; they were mostly converted into textual or semantic descriptions.
It preserves some visual content as semantic or textual detail, including a signature region and chart values and labels, but it does not keep charts as visual objects and instead turns them into prose or text summaries.
Converts a waterfall chart into text that retains nine rate/change values and their increase/decrease directions, but does not keep the chart as a visual object.
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.
Provides a documented API key and multiple functions for integration, and the report says extraction can be run as a fully automated API call with no manual correction, UI interaction, or post-processing required to produce usable output.
Preserves a low-visibility marking through a generated descriptive attestation instead of dropping the region, so a blurred stamp remains represented in the extracted output.
▸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 well2 mixed6 findings
Processed long mixed-content PDFs end-to-end, but quality degraded on hierarchy and complex table reconstruction in larger documents.
It handled long mixed-content reports end to end, preserving reading flow and producing both page-wise and consolidated markdown outputs, but hierarchy flattened in some places so long-document consistency was only partial.
The parser produces both page-level files and a consolidated markdown document in the same export, supporting localized inspection and full-document consumption for a long report.
▸Reading Order & Structure3/56 worked well2 mixed2 failed10 findings
Reading flow was often preserved, but hierarchy was inconsistent, with flattened TOCs and missed section levels.
Generally preserves document hierarchy and reading flow, with headings and supporting text staying aligned in most reports and scanned pages, but it can flatten the heading tree or table-of-contents structure and can lose distinctions such as title vs abstract.
Preserves section-level reading order through most of a long mixed-content annual report, but the reconstructed heading tree becomes flattened in some areas instead of staying fully hierarchical.
▸Table Preservation3/55 worked well1 mixed4 failed10 findings
Handled some layered financial tables well, but multilevel headers and complex scanned tables lost structural fidelity.
It preserved several layered financial and multicolumn tables with headers and row-to-value relationships intact, but broke complex scanned tables and flattened hierarchical structure when the layout was more demanding.
Reconstructs a layered financial table into a usable structured table while keeping the relationships between headers, rows, and corresponding values intact.
Tool input
Tool output
▸Visual Content Retention4/54 worked well4 findings
Charts, signatures, and other visuals were retained as page-linked assets in the output folders rather than being dropped.
Retains non-text visual content as separate, source-linked assets, including charts, signatures, and a scanned stamp region, rather than burying them in a text-only extract.
Charts are exposed through page-wise markdown files and visual assets, keeping the extracted visual content linked to its original document location.
▸Markdown Quality4/54 worked well4 findings
Exported usable overall and page-wise Markdown files in downloadable ZIPs, though structure could flatten in places.
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.
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.
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.
Completes conversion on all three long PDFs tested here—an 84-page hybrid report, an 18-page table-heavy report, and a scanned research paper—and returns markdown exports for each.
Handles an 84-page mixed-content report while keeping heading order and section relationships aligned across tables, charts, and scanned signatures.
▸Reading Order & Structure4/56 worked well6 findings
Preserves section order and document hierarchy well across long hybrid and scanned documents.
It consistently preserved reading order and document structure, keeping headings, hierarchy, and narrative flow aligned even in table-heavy, multi-column, scanned, and long hybrid reports.
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 well2 mixed1 failed6 findings
Keeps ordinary and multi-section tables mostly intact, but multi-header and hierarchical tables lose headers and relationships.
Generally preserves financial tables with row/column relationships and aligned headers in markdown, but it is only partially successful on complex multilevel tables and struggles with hierarchical tables in scanned pages.
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 well2 mixed1 failed4 findings
Extracts chart data and signature content, but visuals are represented as parsed data rather than faithfully retained images in place.
It preserves some scanned-page visual content like handwritten signatures and degraded stamp text, but embedded figures are not retained as visual objects and the stamp text can pick up symbol-level OCR errors.
Captures degraded stamp text well enough to preserve the Ernst & Young reference, but introduces a symbol-level OCR error by rendering an ampersand as a plus sign.
Tool input
Tool output
▸Text & OCR Completeness4/52 worked well4 mixed6 findings
Covers scanned signatures and blurry text with few omissions, but complex scanned tables still break down.
It generally recovers readable scanned signature-page and stamp text, including signatory names, dates, and signature-related annotations, but the handwritten autograph itself can be only loosely transcribed and symbol-level OCR errors like rendering the ampersand as a plus sign still show up.
Detects handwritten-signature content from a scanned page and returns it as readable text, including signer names and signature-related annotations.
Tool input
Tool output
▸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.
Exposes API-key access and documentation from the home page, giving the tool a built-in API entry point alongside the UI workflow.
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.
▸Markdown Quality4/53 worked well3 findings
Outputs usable copyable markdown with clear structure, though it is not a downloadable export.
Produces usable markdown rather than a flat text dump, with clear section headings, a figure block, and bullet lists when present.
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 Handling3/53 struggled3 findings
Handles long mixed-content PDFs, but quality drops on split scanned inputs and some structural fidelity degrades in harder documents.
It struggled with complex scanned documents, because long scanned papers had to be split into separate PDF inputs before processing, breaking continuity across the original file.
Requires scanned PDFs above 1 MB to be split into separate files before processing, which breaks continuity across the original long document.
▸Reading Order & Structure3/51 worked well1 struggled3 failed5 findings
Document-level structure is often preserved, but TOC hierarchy, section boundaries, and some scanned-document ordering degrade.
It preserved document-level hierarchy in one case, but generally flattened structure by losing nested section relationships, document hierarchy, and block separation.
Converts a hierarchical table of contents into a flat list, removing the nested section relationships and indentation cues.
▸Table Preservation4/55 worked well1 mixed1 struggled2 failed9 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.
It usually preserved table structure, including row-and-column relationships, hierarchical grids, grouped-column layouts, and scanned table relationships, but it sometimes flattened dual-header tables, misplaced currency symbols, and broke grouped-column continuity when intervening text appeared.
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 mixed1 failed4 findings
Charts, figures, and images are kept in place and remain visually integrated in the markdown output.
It generally kept embedded charts and images in the parsed layout, but it dropped handwritten signatures entirely.
Keeps embedded charts and images integrated into the parsed document layout for the 84-page hybrid earnings report, rather than separating or dropping them.
▸Text & OCR Completeness4/51 worked well1 mixed1 failed3 findings
Generally recovers readable text well, but misses handwritten signatures and shows some OCR/structure gaps on scanned content.
It recovered dense OCR text from a scanned research page, including the report header, abstract, keywords, and opening paragraphs, but did not recover handwritten signatures, which disappeared from the parsed output while the surrounding printed text remained.
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 well1 struggled4 failed6 findings
Hierarchy works in parts, but multicolumn and scanned documents lose paragraph order and section structure.
It preserved source order in at least one bullet-heavy narrative section, but repeatedly flattened headings, signatures, and multi-column layouts so reading order and hierarchy often broke down.
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 well2 mixed1 struggled2 failed6 findings
Reconstructs native financial tables well, but complex headers and some table layouts become misaligned in other documents.
It usually preserved row/value alignment and structural fidelity in financial tables, but in more complex tables the headers drifted or were reconstructed incorrectly, leaving an inconsistent layout.
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.
▸Visual Content Retention2/51 struggled4 failed5 findings
Charts and figures are converted into text/value extraction rather than preserved as visual assets in the right position.
It consistently failed to retain visual content, replacing waterfall charts, a scanned chart, and handwritten signatures with text-first or raw delimiter-separated output instead of preserving the original visual form.
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
▸Text & OCR Completeness4/52 mixed1 struggled3 findings
Covers most readable content and handles scanned pages, but some currency symbols and structural details are missed.
It usually preserved the table values, but it repeatedly missed currency symbols, so the OCR was not fully complete.
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.
Tool input
Tool output
▸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.
Provides documented API-key access for endpoint use.
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.
Good at basic OCR and section hierarchy, but weak on tables, charts, and other visual content in complex documents.
▸Complex Document Handling2/52 mixed1 failed3 findings
The tool processed long, mixed-content PDFs, but quality degraded on complex tables, chart pages, and scanned layouts.
Handles some section/body hierarchy in isolated parts, but loses structural boundaries in more complex table layouts, with cells misaligned, merged incorrectly, or lost entirely.
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 mixed1 struggled2 failed7 findings
Section hierarchy was preserved in some places, but paragraph flow and page-level order broke in scanned and dense documents.
It preserved local reading order and hierarchy in some native and scanned layouts, but misordered top-of-page content in scanned papers and fragmented table-heavy reports.
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 well2 struggled2 failed5 findings
Simple and grouped tables were sometimes usable, but multi-level headers and complex row/column relationships were often misaligned or lost.
It preserved grouped-column table organization in the scanned paper example, but misaligned rows, columns, and values on the financial table and broke multi-level header and grouped-table structure as complexity increased.
Preserves grouped-column table organization in a scanned paper, keeping the internal table structure largely intact in the shown example.
Tool input
Tool output
▸Visual Content Retention1/55 failed5 findings
Chart values were extracted in linear form, but figures, chart semantics, and handwritten signatures were not retained as visual content.
It consistently preserved surrounding text and some extracted numbers, but repeatedly dropped the visual content itself—images, the handwritten signature, and chart layout/semantics—so the output was not visually faithful.
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
▸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.