Rev. 0.1 · Issued 2026 · 73 entries

Field Manual

Utilities for the working day: encoding, networks, time, certificates and conversions. Everything runs in your browser.

§0 Intake

Paste anything and the manual suggests where to look

§ Contents

1 Encoding
1. Base64 1-01
  Encode and decode Base64, standard or URL-safe, UTF-8 aware.
2. URL encoding 1-02
  Percent-encode and decode text as URI component, full URI or form data, and split URLs.
3. HTML entities 1-03
  Escape text for HTML and decode named, decimal and hex character references.
4. Unicode inspector 1-04
  Show each code point with name, UTF-8 and UTF-16, find invisible, bidi and look-alike characters, normalise.
2 Networking
1. CIDR and subnet calculator 2-01
  Network, broadcast, host range, wildcard and RFC classification for an IPv4 prefix.
2. IP address 2-02
  IPv6 and IPv4 address forms, special ranges, integer, binary and reverse DNS name.
3. DNS lookup 2-03
  Query A, AAAA, MX, TXT, CAA and other records over DNS over HTTPS, with DNSSEC flag and TTLs.
3 Time and dates
1. Unix timestamp 3-01
  Epoch seconds, ms, µs or ns to human dates and back, with ISO week and time zones.
2. Date difference 3-02
  Years, months and days between two dates, totals, and Danish working days without holidays.
3. Add and subtract time 3-03
  Date plus or minus a duration or ISO 8601 period, or N Danish working days, with weekday and ISO week.
4. Cron expression 3-04
  Cron schedule in plain English, field by field, with the next 10 runs in any time zone.
5. Windows and other epochs 3-05
  FILETIME, AD lastLogonTimestamp, Excel serials, .NET ticks, GPS, NTP, Cocoa, snowflake ids, UUID and ULID times.
4 Security and crypto
1. Hash generator 4-01
  MD5, SHA-1 and SHA-2 digests and HMAC of text or a local file, with checksum compare.
2. JWT decoder 4-02
  Decode a JSON Web Token, check its time claims and verify HS, RS, PS or ES signatures.
3. Password generator 4-03
  Random passwords and EFF diceware passphrases from the browser CSPRNG, with exact entropy.
4. Certificate decoder 4-04
  Decode X.509 certificates, chains and CSRs: names, validity, key, extensions, fingerprints.
5. CSR and key generator 4-05
  Generate a key pair and a signed PKCS#10 request with subject and SANs, in the browser.
6. SSH public key 4-06
  Fingerprints, type and size of OpenSSH public keys, authorized_keys and known_hosts lines.
7. TOTP codes 4-07
  Current, previous and next TOTP or HOTP codes from a base32 secret or otpauth:// URI.
8. CVSS calculator 4-08
  CVSS v3.1 base, temporal and environmental scores from a vector or by metric; v4.0 explained.
9. Secret scanner 4-09
  Find API keys, tokens, private keys and passwords in text before sharing it, and redact them.
5 Data formats
1. JSON formatter 5-01
  Validate, pretty-print, minify and sort JSON, with line and column for errors.
2. Text diff 5-02
  Compare two texts line by line with word highlights, unified or side by side.
3. Regex tester 5-03
  Test JavaScript regular expressions: highlighted matches, groups, replace preview, explanation.
4. CSV and JSON 5-04
  View CSV as a sortable table and convert between CSV, JSON and Markdown.
5. YAML and JSON 5-05
  Convert YAML to JSON and back, with anchors, merge keys and YAML 1.1 pitfalls flagged.
6. XML formatter 5-06
  Pretty-print, minify and check XML for well-formedness, with an XPath tester.
7. Table converter 5-07
  Paste a table from Excel, Google Sheets, Markdown, HTML or CSV and get Markdown, HTML, ASCII, CSV, TSV or JSON.
8. SQL formatter 5-08
  Format or minify SQL: clauses, joins, conditions, subqueries, CASE and CTEs laid out.
6 Numbers and units
1. Number base converter 6-01
  Binary, octal, decimal, hex and any base to 36, with two's complement and bit view.
2. Byte units 6-02
  Bytes in decimal and binary units and bits, the TB vs TiB gap, and transfer time.
3. Bitwise calculator 6-03
  AND, OR, XOR, NOT, shifts and rotates at 8 to 64 bits, signed or unsigned, with popcount, masks and a bit grid.
4. IEEE 754 inspector 6-04
  Float32 and float64 bits: sign, exponent, mantissa, the exact stored value, neighbours and ULP.
5. Unit converter 6-05
  Length, area, volume, mass, temperature, speed, pressure, energy, power, data rate, angle and time, from free text like 5 ft 11 in.
6. Percentages and ratios 6-06
  X % of Y, percent change and percentage points, VAT in and out, ratios like 16:9 and aspect resize.
7. Statistics on a list 6-07
  Paste numbers: mean, median, mode, variance, standard deviation, percentiles, outliers and a histogram.
8. Roman numerals 6-08
  Roman numerals to numbers and back, 1 to 3999, with the decomposition and strict checks.
7 Text
1. Case converter 7-01
  Convert text or identifiers to camelCase, snake_case, kebab-case, Title Case and more.
2. Line tools 7-02
  Sort, dedupe, trim, number, wrap, shuffle and count lines, as a pipeline of steps.
3. Extract from text 7-03
  Pull IPs, CIDRs, URLs, domains, emails, hashes, CVEs and other indicators out of text.
4. Text statistics 7-04
  Count characters, words, sentences and bytes, estimate reading time and SMS segments.
5. Slug and filename 7-05
  Turn a title into a URL slug, or any text into a filename that is safe on Windows, macOS and Linux.
8 Email and identity
1. Email header analyser 8-01
  Trace the Received path of a message with delays per hop, and read its SPF, DKIM, DMARC and ARC results.
2. SPF record 8-02
  Explain an SPF record term by term, or look up a domain and count its DNS lookups against the limit of 10.
3. DMARC record 8-03
  Explain and build v=DMARC1 policy records, with an optional DNS over HTTPS lookup.
4. DMARC report viewer 8-04
  Open a DMARC aggregate report (XML, gzip or zip) and see which servers send as your domain and whether they pass.
5. LDAP DN 8-05
  Parse distinguished names, convert to canonical name form, and escape values for DNs and search filters.
9 Web and developer
1. HTTP status codes 9-01
  Every registered HTTP status code with meaning, typical cause and cacheability, plus common nginx and Cloudflare codes.
2. chmod calculator 9-02
  Unix permissions between checkboxes, octal (4755), symbolic (-rwsr-xr-x) and chmod forms, plus umask.
3. Semver 9-03
  Parse and sort SemVer 2.0.0 versions and test npm ranges (^ ~ x || hyphen) against a list.
4. Cookie and Set-Cookie 9-04
  Read Cookie and Set-Cookie headers: values, attributes, prefixes and SameSite, with security warnings.
5. Content-Security-Policy 9-05
  Explain a CSP directive by directive, flag risky sources and missing directives, or build a new policy.
10 Visual and media
1. Colour converter and contrast 10-01
  Convert between HEX, RGB, HSL, HWB, OKLCH and CMYK, and check WCAG contrast between two colours.
2. QR code generator 10-02
  Make QR codes for text, links, Wi-Fi, contacts, 2FA secrets, email and SMS, as SVG or PNG.
3. Image metadata 10-03
  Read Exif, GPS, XMP and IPTC from JPEG, PNG and WebP files, see what a photo reveals, and strip it losslessly.
11 Electronics
1. Resistor colour code 11-01
  4, 5 and 6 band colour codes both ways, nearest E12, E24 and E96 values, SMD markings.
2. Ohm's law and dividers 11-02
  V, I, R and P from any two, voltage dividers with E24 picks, LED series resistors, series and parallel.
12 Journalistic units
1. Journalistic units 12-01
  A quantity in newspaper units: football pitches, elephants, Rundetårne, floppy disks. Every reference sourced.
13 Windows and Active Directory
1. Windows SID 13-01
  Security identifiers between string, hex and Base64 objectSid, with well-known SIDs and RIDs named.
2. userAccountControl flags 13-02
  Decode and build AD userAccountControl and msDS-SupportedEncryptionTypes, with risky flags and LDAP filters.
3. GUID and AD objectGUID 13-03
  GUID strings to AD byte order, Base64 objectGUID and LDAP filters, UUID version info, new v4 and v7.
14 Cloud and infrastructure
1. Kubernetes resource units 14-01
  CPU and memory quantities to cores and bytes, Mi versus M, sums of requests and limits, pod QoS class.
2. Cloud resource IDs 14-02
  Split and check AWS ARNs, Azure resource IDs and Google Cloud resource names.
15 Operations and capacity
1. SLA and uptime 15-01
  Availability percentage to allowed downtime and back, composite availability and MTBF/MTTR.
2. RAID calculator 15-02
  Usable capacity, fault tolerance, theoretical speed, rebuild time and URE risk for RAID 0 to 60.
3. Backup retention 15-03
  GFS retention to restore points, oldest restore date and storage estimate, plus a 3-2-1-1-0 check.
16 Validation and test data
1. Check digits 16-01
  Validate or compute IBAN, Luhn, EAN/UPC, ISBN, ISSN, CVR and CPR check digits, type detected from the input.
2. Test data generator 16-02
  Fake but well-formed names, emails, phones, addresses, IBANs, test cards and UUIDs as CSV or JSON.
17 Education
1. Grade scales 17-01
  Danish 7-point scale, ECTS grades and the old 13-scale side by side, plus an ECTS-weighted average.
2. ECTS workload 17-02
  ECTS to study hours and back, weekly load per course, and a semester planner.
18 Reference
1. ASCII table 18-01
  ASCII 0 to 127 in decimal, hex, octal and binary with control names, caret notation and escapes; Latin-1 and Windows-1252 too.
2. Spelling alphabets 18-02
  Text to NATO/ICAO or Danish spelling alphabet, with case and symbols named, for reading out passwords.
3. Port reference 18-03
  Well-known and common TCP/UDP ports with IANA service names and notes on services that should never be exposed.

Field Manual

§0 Intake

§ Contents

1 Encoding

2 Networking

3 Time and dates

4 Security and crypto

5 Data formats

6 Numbers and units

7 Text

8 Email and identity

9 Web and developer

10 Visual and media

11 Electronics

12 Journalistic units

13 Windows and Active Directory

14 Cloud and infrastructure

15 Operations and capacity

16 Validation and test data

17 Education

18 Reference