AI Collaboration Builds Open-Source PDF Tool
No_Split11911 · reddit · 2026-07-17
The author released an open-source Windows PDF tool, Open PDF Studio, aiming to replicate the daily workflow of Adobe Acrobat: covering organizing, annotating, filling/signing, forms, true redaction, OCR, comparison, encryption, compression, repair, watermarking, and exporting, plus CLI subcommands, with no ads, telemetry, or paywalls.
The post highlights not just the product, but its build process:
- The author first had Fable 5 write the prompt for its next steps, then fed that prompt back into it.
- The model produced a complete build plan, reviewed in phases via multiple subagents; it also maintained a backlog/deferred list, reprioritizing constantly like a mini project manager.
- Due to quick exhaustion of weekly quotas, Opus 4.8 and Sonnet 5 took over the bulk of the work midway; after quotas reset, Fable 5 returned to clear the deferred items, ultimately completing the v2.0.0 tag that day.
- The author notes the project wasn't built from scratch but evolved from the previous SpectraPDF; this upgrade from a "simple alternative" to an "Acrobat-level workbench" is the source of the screenshots and token bills.
- Over 4 days, it consumed 2 billion+ tokens; the costs in the post are calculated using equivalent API pricing, though the author actually used subscriptions, making it affordable but subject to weekly limits.
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